Games can use thier own form of virtual memory and temporary files, depending on the development, although some games, especially older titles might require Windows virtual memory to be available.
Prefetch and memory compression only affect loading often used apps (so might help with launching a game if used often). Game assets will be decompressed by the CPU then passed to the GPU so it wouldn't make sense to use memory compression on a running games assets and processes.
Lots of other types of Windows processes and apps may well have issues if there is no virtual memory available so it really doesn't make sense to disable it, but you do what you want to with your machine.
Also with two different sized memory modules installed you will have only 16GB running in dual channel mode (if it is indeed working), the other 8GB (the other half of the 16GB module) is running in single channel mode.
Depending on how the iGPU is assigned memory it could well be using single channel mode or if not then it is reducing the amount of dual channel mode memory available to other processes.
