Admittedly, the characters in fpsc stock media do lag the frame-rate after placing about 2 enemies, but instead of creating a thread with you expressing your fustration towards the subject, think about whether anyone here can actually fix this problem.
In the games i'm experimenting with at the moment, i use fog which seems to increase the frame-rate quite a lot most of the time, and I'm also creating more of a psychological aspect to the games; not everyone wants to know that an enemy is around every corner, if you make the games have few enemies jumping at you from the most unlikely places, not only will it make the player jump, it will increase the frame-rate. If you haven't played doom 3, then I suggest you try it, then you will see what I'm on about.
I personally think that Fps Creator was a bargain for what you get, maybe some people think that you can only place a few enemies, keys, weapons and get going, but you can do so much more when you learn more about it, I'm still learning loads about it now, and I've had it just about when the final version came out. If you want a higher frame-rate or a better game, then get Torque Game Engine, even though I'm quite able in it now, I still think FPSC gives me more opportunities, basically because of it's simplicity.
All I'm saying from that is that you should find ways of getting round your problems instead of telling us them, because all I can say really for this problem is: use fog, less enemies, use more scripting, play doom 3 and be thankful to TGC. If you are still concerned, either spend 30yrs trying to master Torque Game Engine, wait for FPS Creator X10, or try 2D game development.
evil lies within all of us...we just don't know it yet