A few months ago I decided to purchase and install the whole suite of AVG software on my laptop at home - an ageing Dell XPS machine. It ran through everything telling me what programs should be stopped to improve performance, which things could be improved etc. Also, when I plugged it into the power, it ran various things to make the machine run better, restoring a battery mode when I was disconnected from the mains.
It all looked quite clever, and I was quite happy.
however, a few months on and the system just seemed so slow. Just unplugging the mains cord resulted in delays where the AVG tried to improve performance for running on a battery. Pop ups started telling me to do this that and the other. Really annoying.
It got to a point where I uninstalled everything related to AVG.
Since then, everything is really good again!