Memory issues? I have have never had any memory issues with Firefox and it's been almost crash free now for the last six releases.
It's 2016 now so maybe it's time to upgrade your box and it's 4 GB of RAM.
EDIT: How is Firefox eating up to 3Gb of RAM on your machine? I never seen mine go over 1.5GB and that's been after a week of not closing it (64-bit version/no Flash installed).