Build Identofire: http://hg.mozilla.org/mozilla-central/rev/90857937b601 Mozilla/5.0 (Windows NT 6.1; WOW64; rv:19.0) Gecko/19.0 Firefox/19.0 ID:20121013030542 I noticed the performance regression when I test Bug 801267. Steps to reproduce: 1. Disable HWA ( Tools > Options > Advanced > General > uncheck "Use hardware acceleration when available" 2. Rrestart browser. 3. Open http://paperjs.org/examples/meta-balls/ 4. Move mouse in the right pane Actual results: Drawing is extremely slow Regression window(m-c) Good: http://hg.mozilla.org/mozilla-central/rev/b1775e08bb16 Mozilla/5.0 (Windows NT 6.1; WOW64; rv:19.0) Gecko/19.0 Firefox/19.0 ID:20121012032003 Bad: http://hg.mozilla.org/mozilla-central/rev/83e8792a147a Mozilla/5.0 (Windows NT 6.1; WOW64; rv:19.0) Gecko/19.0 Firefox/19.0 ID:20121012040504 Pushlog: http://hg.mozilla.org/mozilla-central/pushloghtml?fromchange=b1775e08bb16&tochange=83e8792a147a Regression window(m-i) Good: http://hg.mozilla.org/integration/mozilla-inbound/rev/cea04d0eb7c9 Mozilla/5.0 (Windows NT 6.1; WOW64; rv:19.0) Gecko/19.0 Firefox/19.0 ID:20121011155703 Bad: http://hg.mozilla.org/integration/mozilla-inbound/rev/f283941dbf75 Mozilla/5.0 (Windows NT 6.1; WOW64; rv:19.0) Gecko/19.0 Firefox/19.0 ID:20121011163903 Pushlog: http://hg.mozilla.org/integration/mozilla-inbound/pushloghtml?fromchange=cea04d0eb7c9&tochange=f283941dbf75 Suspected: Bug 800287 or Bug 795674

Should be fixed by https://hg.mozilla.org/integration/mozilla-inbound/rev/007e3dea2e57, as part of bug 795674.

I confirmed the problem was fixed in latest m-i. http://hg.mozilla.org/integration/mozilla-inbound/rev/007e3dea2e57 Mozilla/5.0 (Windows NT 6.1; WOW64; rv:19.0) Gecko/19.0 Firefox/19.0 ID:20121014192607