1. Open Mozilla Firefox.
2. Click the 3-bar menu button (≡) in the top right corner.
4. Scroll down the General page and look for the Performance section.
5. Uncheck ‘Use recommended performance settings.’ Additional settings will be displayed.
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6. Tick the checkbox beside 'Use hardware acceleration when available' if you want to activate hardware acceleration.
-OR-
Uncheck 'Use hardware acceleration when available' if you want to turn off hardware acceleration.
7. Restart Mozilla Firefox after you have made the desired changes.