What file are you using to verify size changes? Our standard metric is jquery.min.js.gz, and you'll be able to see it directly from `grunt` if you rebase onto 91d57647e9700de1a3693a400c85688c90304dde. I'm certain, for instance, that you'll achieve better compression by declaring `options` third rather than first and skipping the initial assignment to `optionSet`. There are even greater savings to be had by abandoning `jQuery.each` in favor of native iteration.

Also, looking at this with fresh eyes, I'm pretty sure you can combine the two tests here and just set `elem.selectedIndex = -1` whenever `optionSet` is falsy.