Its been more than three years I am using quickheal as a primary antivirus for all my systems. My PC has a older version of quickheal and I have recently updated my laptop with Quick Heal Internet Security 2015 and Quick Heal Total Security 2015 for my Tab.
Its not like I never faced problem with my laptop in the presence of antivirus in my system, but that problems are too minor to mind plus I have seen performance of other antivirus on my friends system, so I can clam, that quick heal is way better.
It slows down your system a little bit, but again every antivirus will dose that to your system.
I don’t update my antivirus frequently still I never get any infections from new threats.
Plus its affordable.