Are you on Windows by any chance? I experience that with Firefox only when I use Windows (i.e. almost never, fortunately). I switched to Firefox on my main computer (Linux) a year ago and I could not be happier. It consumes much less memory than Chrome, it's way faster (that's my impression, I haven't measured that in any way) and it is a lot more customizable. I removed a lot of stuff from the context menu for example.

As a bonus, it isn't made by Google. I was a hardcore Google fan a few years ago, but after seeing what they are doing with Chrome and the internet, I just could not keep using Chrome any longer.