We are aware of some performance problems on Windows 98, especially because of apache 1.3 which is known to be slow under windows.
Do you get this on every page load? Even if you reload a page?
The accelerator we use for the Linux/FreeBSD installers is not available on windows, but we are considering to bundle mmcache (http://www.turcksoft.com/en/e_mmc.htm) with the windows installers.