Plus it's written in LUA, I don't know it.. it's may be faster than lite-c, I don't even know.
LUA is interpreted and thus by definition slower than Lite-C. Given a good compiler, C is one of the fastest languages available. Here is a nice comparison:
http://shootout.alioth.debian.org/u32/wh...&calc=chart(I'm not saying that the Lite-C compiler produces equal fast output as GCC, plus I'm also pretty sure that Clang-LLVM can produce even faster code).
First of all, I'm not professional such as Valve guys... Should that mean that there is no way for me to make cool and fast FPS game?
I've made really fast movement and weapons (did everything I could do to make it fast!), but placed grass models and 20-40 fps?!
No, I'm not saying that you can't do it. I just wanted to point out that everyone has to put some thoughts into performance.
Plus, your problem was already pointed out by Nils, the problem is the heavy alphablending. A task which isn't done by the engine but by your graphic card so blame it if you want to blame something
