content.notify.interval [Integer] *Create - The value in microseconds for this preference (where 1,000 microseconds = 1 millisecond = 1/1000th of a second) determines how long Firefox buffers network data before displaying it.
By default the value is 120000 microseconds (120 milliseconds).
Note that for this setting to work, a new Boolean preference called content.notify.ontimer must also be created and set to True.
content.switch.threshold [Integer] *Create - This setting determines how long Firefox waits for user input (mouse or keyboard input) before switching to a less-responsive but less system-intensive low frequency mode while loading a page.
Lowering this setting may improve display speed in Firefox, however it will also increase CPU usage to do so.
Experiment with this setting, either raising it or lowering it to see if the results are beneficial on your system.
The default value is 750000 microseconds, but raising this value might keep Firefox more responsive at the cost of greater system load and slightly longer page loading times. Note that for this setting to work, a new Boolean preference called content.interrupt.parsing must also be created and set to True.
config.trim_on_minimize [Boolean] *Create - This setting only works in Windows, and determines whether Firefox - much like other Windows applications - reduces its memory usage after a period of time when minimized to the Taskbar.
If set to True, it will use less memory when minimized, which is useful for systems with low RAM and multiple open applications.