Turns out that the standard min/max functions were slow for
some reason, and simple if statements are much faster. This
simple change improves render times by over 30%. Crazy.
This, of course, depends on the simd ops being there, which
currently they are not. But in the future, hopefully this will
make things speedy. Will need to test, of course.
It was using bounds-checked indexing in the basic operations. Now
it's using non-bounds-checked indexing, since all of the indexing
is constants that we know to be within the bounds.
