The release (and production) builds of ANGLE should have the optimizations that they have in the original repository: inline function expansion, intrinsic functions, and whole program optimization. With these changes I'm seeing about 20fps on http://soulwire.github.io/WebGL-GPU-Particles/
Created attachment 208156 [details] Patch
Comment on attachment 208156 [details] Patch Clearing flags on attachment: 208156 Committed r153732: <http://trac.webkit.org/changeset/153732>
All reviewed patches have been landed. Closing bug.