A bit less often than yes, I have measured it.
Leverage native APIs, otherwise check only for @ and go grab another beer.
It is nice to have free powerful stuff, but let's not forget about the standards.
Split, reverse, cast, and the power of 'reduce'.
Wrap semantic blocks, use HTML classes for styling and read the manual.
IE 9 has a hard limit of 4095 selectors per stylesheet. Size does not matter here.