Hi, I have a late 2012 iMac 21.5 16Gb memory. Until the latest update it has generally run pretty well, with very rare spinny balls. Since the upgrade spinny balls are quite frequent and there have been several complete freezes needing a hard restart. On the other hand, on the plus side, we recently had our broadband upgraded from 4Mbs to about 16Mbs, still not excatly High Speed but web browsing (Firefox 50) was very much quicker for a while. Howevere this last few days the web browser has slowed to a crawl yet Speedtest.net still reports around 16Mbs. The only additional thing that may account for it was that I donloaded and installed Scanguard I ran this and it reported just 2 "threats" which I removed. Could this program be causing my problems? Looking at the Activity Monitor it shows Firefox web content using up to 100% of CPU time. Any suggestions how to fix this?