Hi and Welcome to TGC forums, i hope you enjoy your stay, evan if sometimes you get shouted/flamed, its a living :/
Ok, lets get started shall we?
Unfortunally by the way FPSC is built, we are limited to the number of objects we use in our games, also, don't forget, this engine isn't like HL2/Doom3/Quake4.
The only way to fix it, by now (don't forget that FPSC like all the other products are always under patches and upgradess), is to use less objects in rooms and in big open areas use way less objects. Don't place too many enemies in the same place, this will also help.
I still say you should buy FPSC, since with it you can still make really fun games
Details isn't everything.
Regards
DJ
My love is seperated in 2 parts, 1 of them is 3ds Max 7, the other; FPSC.