Problem: IE8 creating multiple iexplore process instances

Note1: I can not disable the IE8 property which creates multiple intances, because my web application is compatible with IE8 only.

This is really the only viable solution, to disable the registry item that creates multiple processes.  However, as far as I know, doing so should not negate any web application's compatibility with IE8.  Can you clarify how doing so would make your application not work?