I was using AVG2014 and found it quite obtrusive. My laptop is a slow B980 @2.4GHz and 2GB RAM.
I went to bitdefender, and it was a pain. It maxed out my RAM, and was always doing something. It also maxed out my hard disk transfer rate, making my pc VERY slow (unusable) for a lengthy time (1 hour). Unistalled it. I might try Avast now.
Also, I am using Win 8.1 64-bit, and I always have a process called 'System' eating up my HDD transfer rate. It can go up to 12MB/S at times too!
I have been noticing it since I removed AVG. Anyone know what it is?
Try AVG uninstaller http://www.avg.com/gb-en/utilities ,it makes sure all AVG files are gone,as to System you should have that listed but yours seems high on usage mine is using memory 0.1MB, HD usage is 0 to 0.1MB on mine its PID 4 and listed as NT kernel and System.