C programming tricks

While programming optimization that makes ones' code completely unreadable is often a bad thing, there are places for it, like that one inner loop of your code that takes up 98% of the program's running time.

What are you tricks for improving performance in C, other than the obvious inline assembly or the like?

AHAHAHAHAHAHAHAHAHAHAHAHAHAHA
FUCKING CLUELESS CPU NOOBS

>>10
YOU BETTER BE JOKING NIGGER. THAT AIN'T OPTIMIZATION AT ALL.
IT IS SHIT CODE
>>11

char **x, **y;
YOU FAIL, FURTHERMORE, http://en.wikipedia.org/wiki/Xor_swap#The_XCHG_instruction
These compilers are more likely to recognize and optimize a conventional (temporary-based) swap than to recognize the high-level language statements that correspond to a XOR swap.
FUCKING NOOB
FUCK