Same as its always been,
Hand coding in assembler, always causes problems for the beginner.
If you want to learn how to write efficient code use a c compiler with the optimisation turned off, look at the code produced.
Some of the more Ludite people on here will shout that you shouldn't use a compiler, but the fact is that compilers don't forget to insert returns, always know whats on the stack and you can modify your source code without breaking everything.You can even have ore than one person working on the project at the same time.