Global Variables performance effect (c, c++)

Question

I\'m currently developing a very fast algorithm, with one part of it being an extremely fast scanner and statistics function. In this quest, i\'m after any performance benefit.

Answer 1

Creating local variables can be literally free if they are POD types. You likely are overflowing a cache line with too many stack variables or other similar alignment-based causes which are very specific to your piece of code. I usually find that non-local variables significantly decrease performance.