I commented on the previous release of FF15 when they fixed the plugin memory leak fixes, but since I've used it a lot for responsive design, I've noticed this

I commented on the previous release of FF15 when they fixed the plugin memory leak fixes, but since I've used it a lot for responsive design, I've noticed this is still a big problem for normal everyday use, even with just two tabs open. I'm not sure what FF15 fixed, but I just don't notice the improvement I was hoping for.