Microsoft may have made Windows 7's installation process faster than Vista's, but an in-place upgrade can still take a little while. Chris Hernandez of the Windows Deployment team has written up a blog post about tests conducted to benchmark the new operating system's upgrade performance, and the results are a little surprising.
For a clean installation of Windows Vista, doing an in-place upgrade to Windows 7 can take as little as 30 to 50 minutes, depending on the hardware. As soon as you pile on more applications and user data, though, the process time increases dramatically.
For a "heavy user" with 125GB of user data, 40 installed applications, 15 "optional components," and modified settings, the upgrade can take 150 to 355 minutes, depending on the hardware—up to six hours, in other words. Meanwhile, a "super user" with 650GB of profile data can look forward to an upgrade time as high as 1220 minutes (over 20 hours) on a "mid-range" system with Vista x86. Ouch.
On the upside, Hernandez says the results show doing an in-place upgrade to Windows 7 was "faster or equal within a 5% threshold" than running a similar "upgrade" process from Vista SP1 to Vista SP1, which suggests the new OS is at least no slower than its predecessor in that regard.