ngryman/speedracer: Collect performance metrics for your library/application.

facebook/prepack: Prepack is a partial evaluator for JavaScript. Prepack rewrites a JavaScript bundle, resulting in JavaScript code that executes more efficiently.

gmetais/grunt-devperf

dieulot/instantclick

InstantClick – JS lib to make your website instant

Juicer - a CSS and JavaScript packaging tool /Ruby - cjohansen.no

cjohansen's juicer at master - GitHub

Plugins | jQuery Plugins

Jiffy Firefox Extension - Documentation