What processor do you have?

That is recommended hardware ans not a requirement

• Pentium 4 or newer processor that supports SSE2
• http://www.mozilla.org/en-US/firefox/20.0/system-requirements/

Firefox should still run on a Pentium 3 processor, but may run slower when necessary with such an older processor.

What is the CPU speed of your processor and how much physical memory do you have?

A lack of a sufficient amount of memory is a much serious cause of Firefox and other programs not running smoothly.

PIII EB

PIII EB 666 MHz with 384 MB of memory. FF19 does run on my old machine, my only concern is that if FF19 requires SEE2 to be present then it might crash my computer (hasn't happen yet.}