For several months I battled with declining performance of my primary Windows 7 VM that I use for work. It'd have decent performance immediately after a reboot, but if the VM remained idle for more than a few hours (and definitely overnight) it'd be as snappy as a slug in molasses in winter. Finally I opened a case with VMware and one of their techs resolved the issue by making the following changes to the guest OS settings:
- Reduced hardware from 4 cores and 8 GB of RAM to 2 cores and 4 GB of RAM
- Turned all 3D graphics off
- Disabled disk buffering
- Performed a VM cleanup
- Performed a Win7 disk cleanup
- msconfig - Startup - Disable All
I subsequently re-enabled all the startup items that were disabled in step six without any performance degradation. Scuttlebutt on various forums tends to place the blame on the disk buffering feature, which would seem consistent with my experience and observations.
For the record, the host OS is MacOS Sierra (10.12) on a Mid-2012 Retina MacBook Pro with 16 GB of RAM and an Aura SSD from OtherWorld Computing.