Mozilla has released Firefox 38.0.5 which contains a fix for this problem (Release Notes). To update your version, see Update Firefox to the latest release.
This article applies to an older version of Firefox (version 38). The issue has already been fixed in your version of Firefox. If you are still experiencing issues with slowness, see Quick fixes if your Firefox slows down.
After the recent update to Firefox 38, some Windows users may notice that Firefox responds more slowly while you type in a search, enter a web address, or navigate its controls, than its prior versions.
Mozilla is currently working on a long-term fix, but if you are affected, you can take these steps to fix the issue yourself:
Turn off hardware acceleration
- In the Menu bar at the top of the screen, click and then select or , depending on your macOS version.Click the menu button
and select .
- Select the panel and the tab.
- Uncheck Use hardware acceleration when available.
- Click the Firefox menu and select .Click the Firefox menu at the top of the screen and select .Click the Firefox menu and select .
- Start Firefox the way you normally do.
Install a current graphic driver
Since the problem mainly occurs when using the Standard VGA Graphics Adapter driver included with Windows, installing a dedicated graphics driver for your hardware will help.
In order to update your graphics driver, see Search for and install new graphics drivers.
