Firefox Lion?

Since updating to Firefox 27.0 running OS X Lion 10.7.5 things have gotten screwy --- slow, delays, glitches, crashes in Firefox. I am wondering if installing the latest Adobe Flash Player and other Adobe updates, has anything to do with it. My Machine is a MacPro 1.1 with 8GB good Ram and 4 internals that test OK.

Any suggested tests welcome.

Peter