This page benchmarks the performance of a collection of matrix libraries most of which are intended for use with WebGL:
glMatrix (v1.2, 2011-12-13), mjs (rev 16, 2010-12-15), CanvasMatrix, EWGL_math (rev 32, 2011-03-15), the math utilities in Google's Closure (svn rev: 1364, 2011-11-3), tdl (commit: 59d484f, 2011-06-03), and Sylvester (v0.1.3, 2007-07-05).
Benchmarks for each library are run in an iframe. Results measure millions of iterations per second of the target operation.

Adapted by Stephen Bannasch from the benchmarks Brandon Jones created in his glmatrix library.
Additional improvements by Gregg Tavares.
Sylvester benchmarks by Felix E. Klee.
JavaScript Plotting library: Flotr; Sortable Table by Andrew Tetlaw.
The source code for these benchmarks can be found here on github. Pull requests quite welcome!