Try putting trigger markers in your level so that when the player walks past one, it activates a character model. This way your frame rate should stay at a nice 30-32. Also making custom media is a good way to go, because you can control how many polygons an object has. Custom weapons should be under 2000, custom characters under 4000, and entities should be under 1000 at most. As mentioned before, FPSC is not a very good engine when it comes to frame rate. FPSC is not timer based, that's why the frame-rate is capped at 32 fps, and pressing the x key to increase frame rate just speeds things up.