This is a new release today from VirtualFilters, a donater to VMware KB articles. Some of the tweaks listed are good ones.
Read vFilters: Maximum Performance Tweaks
Here are my thoughts on things I would feel safe about doing. These changes wouldn't start pegging more resources (as some will if you look at the Document), but actually free up resources in your environment.
Network
- Virtual Hardware 7 - This is a must for everyone putting VMs on vSphere
- Virtual MMU - The actual default is set to "Automatic", not disabled for virtual machines. Only enable hardware MMU if you have newer processors like Nehalems that can utilize the performance boost. TPS will suck, but once memory starts becoming over-committed, regular TPS will start taking place.
- IDE&Floppy - I agree to remove that as well. Rarely will you need a floppy image for a server.
- Logging - Turning off logs will give you a miniscule boost, but then troubleshooting becomes a pain.
- Net.TcpipHeapMax - Setting this to 120 is a must if you change the NFS.MaxVolumes to 64. Likewise, you can set the Net.TcpIPHeadSize to 30
- Vmfs2 Module - I see no point in getting rid of this. I remember a tweet argument going on between @gabvirtualworld (GabesVirtualWorld) and @DuncanYB (Yellow-Bricks) and Duncan pointed out that removing this isn't necessary for "best practice configuration".
- UsbModule - We very well might see USB support in the upcoming releases of vSphere. so take that for what it's worth
Storage
- Disk.DiskMaxIOSize - If you read the KB it relates to ESX 3.5, not vSphere. In vSphere Advanced settings, you can only reduce it to 32mb
- Disk.QFullThreshold & Disk.QFullSampleSize - The KB related to ESX 3.5 Update 4 and use case against 3Par arrays. Be cautious of this change.
HBA BIOS
- I won't even touch these unless recommended by your vendor.
Before changing anything in your environment, use it on a test bed, and read the KBs
Something else I would add is to correctly align your datastore and virtual machine partitions. Most of it's done on the fly, but if you need help, @rickyelqasem from VirtualizePlanet.com has a good tool and article.