compiling/compiler comparison

[deeptech71 at gmail.com]

Compiling. Let's say that the project is debugged and working. The 
performance is of the highest priority.

Does the executable code quality depend only on the compiler? Comparison 
between native and cross-compiling?
Is it worth porting the project to GGC if you can download specifically 
optimized .asm code for GCC? What IDEs are currently available that use GCC?

Finally, if someone knows wether microsoft's or GNU's compiler is better 
for generating faster windows code, please?