Solved Where are the speed bottlenecks?


Haydon

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I copied a large folder containing many subfolders and files. Why is the speed going up and down? Is there something like a slowest component or a slowest process? Is there a way to determine what speed bottleneck it is that slows things down? That would provide a pointer as to what kind of upgrade(s) would speed up the machine, at least for the task at hand, would it not?

Malware scans may be subject to similar 'speed going up and down' and 'speed bottleneck' mechanisms. For example, when running a Defender full scan, the file names are flashing by with slow downs every now and then.

Other tasks may have different speed bottlenecks. Where/what are those speed bottlenecks?
 

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Anytime you are dealing with lots of files, especially lots of small files, the transfer speed is going to bounce around like that. It's gotta commit lots of writes to the file allocation table and such.

When you right a large file, like an ISO or a ZIP, it should go substantially faster. Not really sure of any way to speed up that process, it's how it goes.
 

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Try copying the same folders/ files with something like Robocopy with multi-thread switch and/ or zip them to see if there is an improvement.
In general though most media maintains higher throughput with large files rather than small files as there is less write overhead involved, when talking number of files involved.
Even fast media like NAND can suffer from lots of small writes, not because the actual writing to the cells takes time, but because of the overhead generated by a combination of the copy method (OS, application design) and device interface, from connection type through to the device controller and even it's firmware. Test 5 different manufacturers USB 3.0 flash drives on the same machine with the same test files and you would be amazed at the potential for difference in performance.
Spinner type hard disks show this best with sustained performance versus random due to rotational speed of the platters and the heads having to physically move to read/ write data.
 

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    Defender, Malwarebytes
I agree. When I copy a single, large (30 to 50 GB) Macrium Reflect image file (mrimg extension) from my USB 3.1 connected external SSD to my PC desktop the copy speed is quite constant. See photo. If I copy mutiple smaller files then the copy speed fluctuates as others have said.
copy speed.png
 
Last edited:

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    Windows 11 Pro
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    HP EliteDesk 705 G5
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    AMD Ryzen 5 Pro 3400GE
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    8GB DDR4 SDRAM
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    Integrated AMD Radeon Vega 11
    Hard Drives
    256 GB PCIe NVMe M.2 SSD
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    Windows 11 Home
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    DELL Inspiron 15-3576
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    Intel Core i5-8250U
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    8 GB DDR4 - 2400 SODIMM
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    256GB SK Hynix SC311 SATA SSD
Windows User Account Control (UAC) and Windows Defender can affect the copy speed as they are scanning copied files disabling them may help the speed.
 

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    Windows 11
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    HP Pavilion
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    AMD Ryzen 7 5700G
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    Erica6
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    Micron Technology DDR4-3200 16GB
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    Samsung SyncMaster U28E590
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    SAMSUNG MZVLQ1T0HALB-000H1
As others have mentioned already, this is largely due to operating system design if were to consider the same operation running on the same hardware. However, one thing which might make some marginal difference is fragmentation, this isn't as prevalent as it was on older operating systems, although, it can affect the read performance and therefore may make the copy operation faster.
 

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System One

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    Windows 11, Windows 10, Linux Fedora Cinnamon
I agree. When I copy a single, large (30 to 50 GB) Macrium Reflect image file (mrimg extension) from my USB 3.1 connected external SSD to my PC desktop the copy speed is quite constant. See photo. If I copy mutiple smaller files then the copy speed fluctuates as others have said.
View attachment 23038

In the example given, what would it take to raise the speed from 300 MB/s to 400 MB/s ?
 

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System One

  • OS
    Windows 10 Pro
Odd question but I suspect a faster CPU and a higher USB / USB bus spec would do it.
 

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    Windows 11 Pro
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    HP EliteDesk 705 G5
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    AMD Ryzen 5 Pro 3400GE
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    8GB DDR4 SDRAM
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    Integrated AMD Radeon Vega 11
    Hard Drives
    256 GB PCIe NVMe M.2 SSD
  • Operating System
    Windows 11 Home
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    Laptop
    Manufacturer/Model
    DELL Inspiron 15-3576
    CPU
    Intel Core i5-8250U
    Memory
    8 GB DDR4 - 2400 SODIMM
    Graphics card(s)
    Intel UHD Graphics 620
    Hard Drives
    256GB SK Hynix SC311 SATA SSD
Anytime you are dealing with lots of files, especially lots of small files, the transfer speed is going to bounce around like that. It's gotta commit lots of writes to the file allocation table and such.

When you right a large file, like an ISO or a ZIP, it should go substantially faster. Not really sure of any way to speed up that process, it's how it goes.
In addition to what you have mentioned, I think the cluster size of the partition too plays a role. If the cluster size is higher, then it takes even longer to copy small files.
 

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  • OS
    Windows 11
    Computer type
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    HP Envy dv7
    CPU
    Intel Core i7 3630QM
    Motherboard
    HP
    Memory
    16 GB
    Graphics Card(s)
    Intel HD Graphics 4000 & Nvidia GeForce GT 635M
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    IDT High Definition
    Screen Resolution
    1080p
    Hard Drives
    1 TB Crucial MX500 on bay 1.
    1 TB Seagate HDD on bay 2.
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    Windows Defender
@wiganken @x BlueRobot @pparks1
@Haydon and the rest

What one needs is a proper caching system for the Disk I/O subsystem. Most domestic I/O devices have a tiny cache so once it's full the computer essentially goes into a "Wait state" until the Disk I/O system has emptied its cache and more data transfer can proceed.

It's rarely a lack of CPU power that causes slow I/O. First the memory must be sufficient in the computer -- if it's not then a load more I/O's have to be done to the paging devices which slow down the system even more as those "pages" have to be retrieved and processed. However assuming you have enough RAM then you must have not only fast Disks but those must have decently large cache sizes too.

Finally the software must be sensibly written -- if it can "block" data in large chunks before writing to the output device then there will be a lot less I/O requests and transfer will go a lot quicker.

For example in the Linux dd (data / disk duplicator) comand you can specify a data transfer size (dd if=<file/partition/disk> of=<file/partition/disk> bs=xxxM status=progress where the bs parameter specifies the data chunk size.

"here endeth the 1st lesson " !!!!!

Cheers
jimbo
 

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    Windows XP,7,10,11 Linux Arch Linux
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    2 X Intel i7
First, try copying of files/folders with multithreaded read/write/verify, Overlapped I/O, Direct I/O, while avoiding the MFC bottleneck:
It's still faster than Robocopy, noticeably when you're dealing with very long tasks. (Other areas where Robocopy is lacking compared to FastCopy are things like, e.g., error logging of individual files/folders with proper support of special characters in the names of the files/folders that will appear in the log and the ability to let hash codes that can be calculated for file verification be saved, either in the log or in Alternate Data Streams.)

During the copy procedure, if other processes are accessing the same storage device(s), having a caching software solution can help to boost their performance additionally also, albeit there can be adverse effects, specifically in situations when e.g. the amount of RAM and/or SSD space that is consumed by the cache is what causes performane to degrade. These adverse effects can happen as a result from, e.g., other processes receiving a suboptimal amount of RAM space when the RAM cache is comparatively oversized (or, in the particular case of shared bandwidth with an SSD used for caching one or more slower drives such as HDDs and/or the types of SSDs that are comparatively slow e.g. due to their specs and/or due to their being held back, the SSD caching taking up too much bandwidth). It also is possible to use tiered caching and/or use a Ramdisk with or without Dynamic Memory Management (DMM Compacted) optional feature.

This is all in addition to trying to use separate storage devices when possible so as to balance the load by dividing it across multiple hardware components, as part of a combined strategy. But the number of ports hardwired to a controller is limited, as is the total bandwidth capability of the controller, so bottlenecks and the various optimization techniques that exist to steer around them have a bit of a tendency to be multifactorial and complex─although a lot also depends on what the characteristics of the workload are like─so, here's another excellent example of a software product that effectively combines a whole number of different I/O optimization technologies:
 

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    16GB DDR5
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    GeForce RTX 4060 Mobile
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    20Mbit/s up, 250Mbit/s down
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    FF
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    11 Home
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    Medion S15450
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    i5 1135G7
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    16GB DDR4
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    Intel Iris Xe
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    Eastern Electric MiniMax DAC Supreme; Emotiva UMC-200; Astell & Kern AK240
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    2TB SSD internal
    37TB external
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    Logitech G402
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    Logitech K800
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    20Mbit/s up, 250Mbit/s down
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    FF
In the example given, what would it take to raise the speed from 300 MB/s to 400 MB/s ?
In that example, it was an SSD connected to a USB 3.1 port.

So, first things first....it's most likely a standard SATA based SSD...so likely going to be limited there to ~500MB/sec. (best case). If it's a less capable SSD, your speeds may be slower...like 240-400MB/sec. This could be the limiting factor.

Next, it's over USB 3.1. This likely means it's a USB 3.2 Gen 1 type device, which is limited to 5Gbps. In theory, math says that's about 640MB/sec as the max here. Generally speaking, about 85%-90% of max is what is achieveable as there is some overhead. So, think 540 to about 580MB/sec is what you can expect.


For myself, I bought a Mokin 10Gbps external NVMe enclosure (about $20), then I bought a Crucial P2 1TB NVMe (~$90) that is capable of about 2400MB/sec read and 1800MB/sec writes. My enclosure at 10Gbps allows about ~1280MB/sec max throughput. It plugs in via a USB 3.2 Gen 2 port, or USB-C port. I get about 1100MB/sec to this drive. That's my fastest external drive that I have.
 

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    Windows 11 Pro
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    PC/Desktop
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    Beelink SEI8
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    Intel Core i5-8279u
    Motherboard
    AZW SEI
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    32GB DDR4 2666Mhz
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    Intel Iris Plus 655
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    Intel SST
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    Asus ProArt PA278QV
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    2560x1440
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    512GB NVMe
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    NA
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    NA
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    NA
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    NA
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    500/50
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    Edge
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    Defender
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    Mini PC used for testing Windows 11.
  • Operating System
    Windows 10 Pro
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    Custom
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    Ryzen 9 5900x
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    Asus Rog Strix X570-E Gaming
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    64GB DDR4-3600
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    EVGA GeForce 3080 FT3 Ultra
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    ASUS TUF Gaming VG27AQ. ASUS ProArt Display PA278QV 27” WQHD
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    2TB WD SN850 PCI-E Gen 4 NVMe
    2TB Sandisk Ultra 2.5" SATA SSD
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    Seasonic Focus 850
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    Fractal Meshify S2 in White
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    Dark Rock Pro CPU cooler, 3 x 140mm case fans
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    Logitech G9 Laser Mouse
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    Corsiar K65 RGB Lux
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    500/50
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    Chrome
    Antivirus
    Defender.
In that example, it was an SSD connected to a USB 3.1 port.

So, first things first....it's most likely a standard SATA based SSD...so likely going to be limited there to ~500MB/sec. (best case). If it's a less capable SSD, your speeds may be slower...like 240-400MB/sec. This could be the limiting factor.

Next, it's over USB 3.1. This likely means it's a USB 3.2 Gen 1 type device, which is limited to 5Gbps. In theory, math says that's about 640MB/sec as the max here. Generally speaking, about 85%-90% of max is what is achieveable as there is some overhead. So, think 540 to about 580MB/sec is what you can expect.


For myself, I bought a Mokin 10Gbps external NVMe enclosure (about $20), then I bought a Crucial P2 1TB NVMe (~$90) that is capable of about 2400MB/sec read and 1800MB/sec writes. My enclosure at 10Gbps allows about ~1280MB/sec max throughput. It plugs in via a USB 3.2 Gen 2 port, or USB-C port. I get about 1100MB/sec to this drive. That's my fastest external drive that I have.

That answers the issue of getting the fastest BackUp on an external medium (y)

Now on to the Full Scans of Windows Defender, what causes it to be hours long (apart from the GBs) ? Can it be made minutes long (with a practical solution) ?
 

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    Windows 10 Pro
Now on to the Full Scans of Windows Defender, what causes it to be hours long (apart from the GBs) ? Can it be made minutes long (with a practical solution) ?
A lot of useful info about that subject can be pulled from this discussion thread:
 

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    11 Home
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    Asus TUF Gaming (2024)
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    i7 13650HX
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    16GB DDR5
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    GeForce RTX 4060 Mobile
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    Eastern Electric MiniMax DAC Supreme; Emotiva UMC-200; Astell & Kern AK240
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    FF
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    Medion S15450
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    i5 1135G7
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    16GB DDR4
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    Intel Iris Xe
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    Eastern Electric MiniMax DAC Supreme; Emotiva UMC-200; Astell & Kern AK240
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    Sony Bravia XR-55X90J
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    3840×2160
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    2TB SSD internal
    37TB external
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    Li-ion
    Mouse
    Logitech G402
    Keyboard
    Logitech K800
    Internet Speed
    20Mbit/s up, 250Mbit/s down
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    FF
That answers the issue of getting the fastest BackUp on an external medium (y)

Now on to the Full Scans of Windows Defender, what causes it to be hours long (apart from the GBs) ? Can it be made minutes long (with a practical solution) ?
So, i rarely run a manual scan with Windows defender, so I don't have a good baseline for understanding the timings. However, I did some testing today.

#1). It says right when you run the scan that it could take 30 minutes or longer. So unsure you are going to be able to drop it to just a few minutes.

I have a testbox, (a beelink mini pc), with a Core i5-8279u CPU that has 4 cores and 8 logical processors. It has a middle of the road NVMe drive running the OS (WIndows 11). The box is used for testing and playing, so it doesn't have a lot on it...only about 60GB used on the drive. Watching it (with Task Manager) while full scanning shows that my CPU is pretty much pegged at 100%. The usage on the NVMe is very low....it's bouncing around normally between 1% and 8%. About 10 minutes into my scan, it's at 400k worth of files scanned, the slider is about 1/4 of the way across and it shows about 22 minutes remaining. When I got to about 75-85% of the way across the slider on this system, I noticed that the CPU dropped off to around 20% on average, and the disk utilization dropped to nothing. (assume we are scanning memory resident files and processes at this point) The estimates for scanning time completion was way off at this point. The slider bar barely moved, and the time just kept going up. Started at 3 minutes then 4, then 6 minutes....and it's been running for 15+ minutes showing that.

On my main desktop, i'm running a Ryzen 9 5900x with 12 cores and 24 logical processors. It has a super fast NVMe (WD SN850 PCIe Gen 4). I have about 1.3TB of files on this box, so a lot more to scan. About 450GB worth is on a standard SATA SSD. Watching this one, my CPU shot up near 100% for about 30 seconds, and then I watched my SSD go up to about 100% usage for a around 30 seconds as well. Now my CPU has stablized out to around 25% and my NVMe is bouncing around between 15% and 80%. It's usually in the 25%-50% range. Occasionally seeing my CPU spike up to 80-90% and when that happens the SSD is also close to getting maxed out as well. When I got to about 75-85% of the way across the slider on this system, I noticed that the CPU dropped off to around 6% on average, and the disk utilization dropped to nothing. (assume we are scanning memory resident files and processes at this point)


On the Beelink mini-pc, the scan lasted 52 minutes and 5 seconds, and scanned 1,676,687 files scanned.

On my desktop, the scan lasted 2 hours and 26 minutes and scanned 4,173,733 files.

From what I can tell, the speed of the CPU and the # of cores seems to make the most difference in the full scan.
 

My Computers

System One System Two

  • OS
    Windows 11 Pro
    Computer type
    PC/Desktop
    Manufacturer/Model
    Beelink SEI8
    CPU
    Intel Core i5-8279u
    Motherboard
    AZW SEI
    Memory
    32GB DDR4 2666Mhz
    Graphics Card(s)
    Intel Iris Plus 655
    Sound Card
    Intel SST
    Monitor(s) Displays
    Asus ProArt PA278QV
    Screen Resolution
    2560x1440
    Hard Drives
    512GB NVMe
    PSU
    NA
    Case
    NA
    Cooling
    NA
    Keyboard
    NA
    Mouse
    NA
    Internet Speed
    500/50
    Browser
    Edge
    Antivirus
    Defender
    Other Info
    Mini PC used for testing Windows 11.
  • Operating System
    Windows 10 Pro
    Computer type
    PC/Desktop
    Manufacturer/Model
    Custom
    CPU
    Ryzen 9 5900x
    Motherboard
    Asus Rog Strix X570-E Gaming
    Memory
    64GB DDR4-3600
    Graphics card(s)
    EVGA GeForce 3080 FT3 Ultra
    Sound Card
    Onboard
    Monitor(s) Displays
    ASUS TUF Gaming VG27AQ. ASUS ProArt Display PA278QV 27” WQHD
    Screen Resolution
    2560x1440
    Hard Drives
    2TB WD SN850 PCI-E Gen 4 NVMe
    2TB Sandisk Ultra 2.5" SATA SSD
    PSU
    Seasonic Focus 850
    Case
    Fractal Meshify S2 in White
    Cooling
    Dark Rock Pro CPU cooler, 3 x 140mm case fans
    Mouse
    Logitech G9 Laser Mouse
    Keyboard
    Corsiar K65 RGB Lux
    Internet Speed
    500/50
    Browser
    Chrome
    Antivirus
    Defender.
So, i rarely run a manual scan with Windows defender, so I don't have a good baseline for understanding the timings. However, I did some testing today.

#1). It says right when you run the scan that it could take 30 minutes or longer. So unsure you are going to be able to drop it to just a few minutes.

I have a testbox, (a beelink mini pc), with a Core i5-8279u CPU that has 4 cores and 8 logical processors. It has a middle of the road NVMe drive running the OS (WIndows 11). The box is used for testing and playing, so it doesn't have a lot on it...only about 60GB used on the drive. Watching it (with Task Manager) while full scanning shows that my CPU is pretty much pegged at 100%. The usage on the NVMe is very low....it's bouncing around normally between 1% and 8%. About 10 minutes into my scan, it's at 400k worth of files scanned, the slider is about 1/4 of the way across and it shows about 22 minutes remaining. When I got to about 75-85% of the way across the slider on this system, I noticed that the CPU dropped off to around 20% on average, and the disk utilization dropped to nothing. (assume we are scanning memory resident files and processes at this point) The estimates for scanning time completion was way off at this point. The slider bar barely moved, and the time just kept going up. Started at 3 minutes then 4, then 6 minutes....and it's been running for 15+ minutes showing that.

On my main desktop, i'm running a Ryzen 9 5900x with 12 cores and 24 logical processors. It has a super fast NVMe (WD SN850 PCIe Gen 4). I have about 1.3TB of files on this box, so a lot more to scan. About 450GB worth is on a standard SATA SSD. Watching this one, my CPU shot up near 100% for about 30 seconds, and then I watched my SSD go up to about 100% usage for a around 30 seconds as well. Now my CPU has stablized out to around 25% and my NVMe is bouncing around between 15% and 80%. It's usually in the 25%-50% range. Occasionally seeing my CPU spike up to 80-90% and when that happens the SSD is also close to getting maxed out as well. When I got to about 75-85% of the way across the slider on this system, I noticed that the CPU dropped off to around 6% on average, and the disk utilization dropped to nothing. (assume we are scanning memory resident files and processes at this point)


On the Beelink mini-pc, the scan lasted 52 minutes and 5 seconds, and scanned 1,676,687 files scanned.

On my desktop, the scan lasted 2 hours and 26 minutes and scanned 4,173,733 files.

From what I can tell, the speed of the CPU and the # of cores seems to make the most difference in the full scan.

Considering that Windows Defender is cloud-assisted, while testing, were you connected to the Internet?
 

My Computer

System One

  • OS
    Windows 10 Pro
Considering that Windows Defender is cloud-assisted, while testing, were you connected to the Internet?
Yes, always connected to the Internet
 

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System One System Two

  • OS
    Windows 11 Pro
    Computer type
    PC/Desktop
    Manufacturer/Model
    Beelink SEI8
    CPU
    Intel Core i5-8279u
    Motherboard
    AZW SEI
    Memory
    32GB DDR4 2666Mhz
    Graphics Card(s)
    Intel Iris Plus 655
    Sound Card
    Intel SST
    Monitor(s) Displays
    Asus ProArt PA278QV
    Screen Resolution
    2560x1440
    Hard Drives
    512GB NVMe
    PSU
    NA
    Case
    NA
    Cooling
    NA
    Keyboard
    NA
    Mouse
    NA
    Internet Speed
    500/50
    Browser
    Edge
    Antivirus
    Defender
    Other Info
    Mini PC used for testing Windows 11.
  • Operating System
    Windows 10 Pro
    Computer type
    PC/Desktop
    Manufacturer/Model
    Custom
    CPU
    Ryzen 9 5900x
    Motherboard
    Asus Rog Strix X570-E Gaming
    Memory
    64GB DDR4-3600
    Graphics card(s)
    EVGA GeForce 3080 FT3 Ultra
    Sound Card
    Onboard
    Monitor(s) Displays
    ASUS TUF Gaming VG27AQ. ASUS ProArt Display PA278QV 27” WQHD
    Screen Resolution
    2560x1440
    Hard Drives
    2TB WD SN850 PCI-E Gen 4 NVMe
    2TB Sandisk Ultra 2.5" SATA SSD
    PSU
    Seasonic Focus 850
    Case
    Fractal Meshify S2 in White
    Cooling
    Dark Rock Pro CPU cooler, 3 x 140mm case fans
    Mouse
    Logitech G9 Laser Mouse
    Keyboard
    Corsiar K65 RGB Lux
    Internet Speed
    500/50
    Browser
    Chrome
    Antivirus
    Defender.
I did a few tests myself and now believe that Windows Defender Full Scan needs the 30 minutes for the OS itself, plus extra time for apps and data.

I will mark this thread 'Solved', thanks to all who responded (y)

Edit: Windows Defender Full Scan is very resource intensive, your apps barely work in spite of MS' "Feel free to keep working". IMHO, you can't run Windows Defender Full Scan in the middle of a busy work day.
 
Last edited:

My Computer

System One

  • OS
    Windows 10 Pro
Edit: Windows Defender Full Scan is very resource intensive, your apps barely work in spite of MS' "Feel free to keep working". IMHO, you can't run Windows Defender Full Scan in the middle of a busy work day.
If the Full Scan in question is a Manual Scan, then it translates to "Feel free to keep looking at how your high CPU load makes working impossible". Whereas if it is a Scheduled Scan, then depending on specs and the specific type/characteristics of the workload that defines a busy work day, you still might be able to pull it off somehow, i.e. by toying with the AvgCPULoadFactor. kek
 

My Computers

System One System Two

  • OS
    11 Home
    Computer type
    Laptop
    Manufacturer/Model
    Asus TUF Gaming (2024)
    CPU
    i7 13650HX
    Memory
    16GB DDR5
    Graphics Card(s)
    GeForce RTX 4060 Mobile
    Sound Card
    Eastern Electric MiniMax DAC Supreme; Emotiva UMC-200; Astell & Kern AK240
    Monitor(s) Displays
    Sony Bravia XR-55X90J
    Screen Resolution
    3840×2160
    Hard Drives
    512GB SSD internal
    37TB external
    PSU
    Li-ion
    Cooling
    2× Arc Flow Fans, 4× exhaust vents, 5× heatpipes
    Keyboard
    Logitech K800
    Mouse
    Logitech G402
    Internet Speed
    20Mbit/s up, 250Mbit/s down
    Browser
    FF
  • Operating System
    11 Home
    Computer type
    Laptop
    Manufacturer/Model
    Medion S15450
    CPU
    i5 1135G7
    Memory
    16GB DDR4
    Graphics card(s)
    Intel Iris Xe
    Sound Card
    Eastern Electric MiniMax DAC Supreme; Emotiva UMC-200; Astell & Kern AK240
    Monitor(s) Displays
    Sony Bravia XR-55X90J
    Screen Resolution
    3840×2160
    Hard Drives
    2TB SSD internal
    37TB external
    PSU
    Li-ion
    Mouse
    Logitech G402
    Keyboard
    Logitech K800
    Internet Speed
    20Mbit/s up, 250Mbit/s down
    Browser
    FF

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