Comment by sumtechguy

Basically if the thing you are doing can be precomputed. Then you can use a lookup table. Then at that point do you have the space for it? Is the time to get it out of memory less than the operation you are caching in the lookup table. Then it could be a good candidate for a lookup table. Many times that can be true. But not always. Even if that is all true you can end up hurting something else because your lookup table evicted something else important from the l1/l2 cache. So you also have to test it in context.