I've been running AVG as my antivirus for about 6 years.of curse I used different version of it until now. But it has a problem with one of its services which is Online Shield service. it using sometimes 100% of the CPU usage for a long time, and make computer so slower as you can think about it. I think that the main problem is the AVG Watchdog service and the AVG resident Shield Service. they are using to much cpu at times.