Build Identifier: http://hg.mozilla.org/mozilla-central/rev/ab2ff3b5611f Mozilla/5.0 (Windows NT 6.1; WOW64; rv:14.0) Gecko/20120323 Firefox/14.0a1 ID:20120323031214 Switch application(Alt+Tab) is very slow when Google Presentation opened. This happens on Windows only. Reproducible: Always Steps to reproduce: 1. Start Firefox and other application(such as Explorer) 2. Login Google 3. Open Google Docs Template Gallery https://docs.google.com/templates?type=presentations&pli=1# 4. Find "Beverage Package" and Click "Use This Template" 5. Wait completion of page loading 6. Switch to other application(Alt+Tab) or click Taskbar button 7. Switch back to Firefox(Alt+Tab) or click Taskbar button Actual results: Switch application(Alt+Tab) is very slow Expected results: Should not slow

In addition to the Steps to reproduce: You may need to repeat Step 6 and Step 7 several times.

Regression window Cannot reproduce: http://hg.mozilla.org/mozilla-central/rev/0c3bd5909e79 Mozilla/5.0 (Windows NT 6.1; WOW64; rv:6.0a1) Gecko/20110420 Firefox/6.0a1 ID:20110420170520 Can reploduce: http://hg.mozilla.org/mozilla-central/rev/46fdf12082d4 Mozilla/5.0 (Windows NT 6.1; WOW64; rv:6.0a1) Gecko/20110421 Firefox/6.0a1 ID:20110421030547 Pushlog: http://hg.mozilla.org/mozilla-central/pushloghtml?fromchange=0c3bd5909e79&tochange=46fdf12082d4 Triggered by: fd8e217b2c84 Jonathan Kew — bug 642589 - expose prefs for tweaking DirectWrite/D2D antialiasing behavior. r=jdaggett

Graphics Adapter Description: ATI Radeon HD 4300/4500 Series Vendor ID: 0x1002 Device ID: 0x954f Adapter RAM: 512 Adapter Drivers: aticfx64 aticfx64 aticfx32 aticfx32 atiumd64 atidxx64 atiumdag atidxx32 atiumdva atiumd6a atitmm64 Driver Version: 8.950.0.0 Driver Date: 2-14-2012 Direct2D Enabled: true DirectWrite Enabled: true (6.1.7601.17776) ClearType Parameters: Gamma: 2200 Pixel Structure: RGB ClearType Level: 50 Enhanced Contrast: 200 WebGL Renderer: Google Inc. -- ANGLE (ATI Radeon HD 4300/4500 Series) -- OpenGL ES 2.0 (ANGLE 1.0.0.963) GPU Accelerated Windows: 1/1 Direct3D 10 AzureBackend: direct2d

The problem does not happen if I disabled HWA.

Alice, may you please check if this has improved at all in the latest Nightly?

The page will be unavailable in 2016. So, I close this bug. no need track.