I've had Firefox (versions 3 onwards) running for weeks at a time and only ever had it using between 400-500MB of RAM. Another thing to check would be what kin

I've had Firefox (versions 3 onwards) running for weeks at a time and only ever had it using between 400-500MB of RAM. Another thing to check would be what kind of ad ons you had installed, since I would imagine that they could have quite a significant impact on memory usage and performance.