Tweaks for enabling advanced networking controls and disabling temporary IPv6 addresses.
netsh interface tcp set global congestion=ctcpIf you have 2GB of RAM or more, use this to bump up your system's file cache.
netsh interface tcp set global time=enabled
netsh interface tcp set global chimney=enabled
netsh interface ipv6 set privacy state=disable
An extra command for slow networks, but breaks Battlefield Heroes.
netsh interface tcp set global ecn=enabled
Use these if you're plugged into a network vs a cable/DSL modem directly.
netsh interface ipv6 6to4 set state state=disabled
netsh interface ipv6 isatap set state state=disabled
netsh interface ipv6 set teredo disable
fsutil behavior set memoryusage 2
Also, if you've got $8-15, go find a 2-4GB "Vista-ready" or "Readyboost" flash drive to plug into your box. Format it as FAT32 (or exFAT in Windows 7), name it READYBOOST (not required), and check its properties for a Readyboost tab. If its compatible, you should be able to select up to 4GB of space to use as a cache. This will speed up slow hard drive access.
* HowToGeek article
* ReadyBoost on Wikipedia