I'm hoping someone can help - I've installed IS and ISBoxer but noticed significant performance issues Vs Keyclone (i.e. main window FPS is 9 running 5 wows)

It did ask me to install an earlier version of directX but this hasn't affected Keyclone when I run it as before.

Specs are:

Intel Core2Duo
6Gig Ram
Geforce 8500GT 512mb
Windows 7 64bit

Is there some configuration i've missed or am I doomed with IS?