Windows 7: Free antivirus is too slow!!

actually theres no fast antivirus but "light" antivirus and its performance depends on the hardware you got. and MSE+MBAM is a good choice suggested by many members in the forum

Well, I want to help you.

If you don't have antivirus installed, your computer is going to be cactus real soon.
Here is what to do:
Install Ccleaner (free) Run the program, and it will get rid of all the crap and temporary internet files. This will unclutter your computer and therefore speed it up a bit.

Install Malwarebytes anti malware, and run that program, and when you see all the red entries, select fix all problems. Now your computer will be less infected. And, this, will help speed up your computer.

At this stage, I suggest stick with Windows Firewall..(even though it is only a light firewall)
Comodo firewall (as a stand alone) is for later , when you get more skilled. It is the best firewall, but a weak antivirus.

Install Avast anti virus (free) as a stand alone . (not it's firewall feature..just the free antivirus) Run that. ( even better.., run the boot-time scan) This will ensure that any stubborn virus' (that re invent) can't Lazarith.

so here is the bottom line.

It is more likely that your computer is infected by Virus / Malware.. than by a legitimate anti virus program, hence the slow speed.

I forgot to mention something.

Don't have two antivirus programs running. It will slow your computer.

Also, don't have two firewalls running. (same reason)

Personally for free Comodo Premium - you get the works mate and what they tell you about it being a hog just isn't true - like everything else it depends on your system.

Myself for Kaspersky @ $0.07 a day (2 year licence - offer on) I cannot for the life of me see why anyone should chase their tail looking for a free one, but if you do CIS comes close.

Forgot to mention do get Malwarebytes - free version - good add on / back up

I too am running comodo internet security premium. it was recommended to me by a friend and so far it seems decent. doesnt seem to slow down the laptop at all.