Several users have reported poor disk performance after updating to Windows 7. Specifically, the Windows Experience Index (WEI) disk score is much lower under Windows 7 than it was under Windows XP or Vista on the same system. There are a few procedures that can dramatically boost disk read and write speeds under the beta OS.
Install Intel Storage (or other) drivers Download and install the Intel Storage Manager Drivers (you can use the files marked for Windows Vista).
The generic drivers included with the Windows 7 Beta may deliver dismal performance for your drive’s chipset. If the Intel drivers don’t work, seek updated drivers from your manufacturer’s website.
Change BIOS settings First, boot into BIOS. This is accomplished by pressing a specific key repeatedly as soon as your computer is turned on (or right after it is restarted). For many computers, the key is F8, but it may be F1, F2, F10, the Delete (del) key or the Escape (ESC) key. Consult your computer or motherboard’s manual or try different keys until you find the right one.
Next check your HDD or storage settings–it may be set to “legacy device.” Change it to “performance” or another setting and restart.
Disable write caching Open the control panel then navigate to Hardware & Sound > Device Manager. Find your main drive then right-click it and select properties. Under the policies tab, uncheck “enable write caching on this device”