I wouldn't exactly call Kaspersky light but I used it's trial once while I was traveling in China and I the load is quite manageable. The only points of slow down that I can remember would be when you plug in a flash drive and it goes to auto scan it, and another thing is when it's downloading and applying an update. But bitdefender has the same issues so I wouldn't consider it to be a huge flawI've only used Avira once or twice in VMs so I cannot speak for it, but each time I've used Kaspersky on an actual machine, it slowed it to the point of being unusable; and I'm not talking about some old slow poke XP machine either. I gave Kaspersky several chances, each and every time it either crashed the system or made it unusable (or almost unusable). I'm not saying it doesn't have great protection, it does, I just simply won't ever use it because of the multiple system gunk-ups it caused.