Scrolling is slow
From MozillaZine Knowledge Base
This article describes how to prevent or work around slow scrolling in Firefox.
Due to bug 202718, scrolling can be much slower when smooth scrolling is enabled. To disable smooth scrolling, go to Tools > Options... > Advanced > General, then uncheck the Use smooth scrolling box in the Browsing section.
Installing proper video drivers for your video card, or updating to the latest drivers, may solve problems with slow scrolling. To update video drivers in Windows, open Internet Explorer, go to Windows Update, select Optional updates and then select Hardware updates.
Disabling hardware acceleration on some video cards and drivers can increase scroll speed. To check hardware acceleration on Windows, right click on the desk top to get the display properties menu. Then select Settings > Advanced > Troubleshoot. This article shows how. For more detailed information on troubleshooting display properties, see this article.
Compiz-fusion (Linux only)
On Linux, turning off compiz-fusion can improve scrolling speed.
Firefox scroll performance issues