I might have discovered the real issue, and it might not be "using Mountain Lion." I have been monitoring the Activity Monitor over the pass few days and discovered Firefox has been spiking in the percentage of CPU used. I have seen it climb to 123.0% (not sure how that is possible). During these observations, I had about twelve tabs pinned and sometimes up to twelve more tabs open. The most real memory used is 1.3GB (I have 4GB installed). Also occasionally, the Firefox plugin, Shockwave would launch using about 2% CPU.
This activity doesn't seem normal. Some sites in the pinned tabs include Facebook, Twitter, Flickr, Google +, Gmail, Yahoo mail, Hotmail, AOL mail, etc. Of these, Facebook and Flickr are the most graphics intensive.
I have not found the culprit yet; however, I solved my problem. Some add-on, extension, or plugin in Firefox was causing the problem it seems. Have been running Firefox in the safe mode now since my last post without the dreaded spinning wheel...isn't that awesome!
I have always trusted mi Apple, Mountain Lion and thank you to all who have added to my body of knowledge ( using the Activity monitor and Console).