What effect does avg antivirus have on the performance of a computer system?

Very little, especially in comparison to others. I install AVG free on all of my customers PC's when I do a new installation for them. I always make sure that it does not do a scan on start up because that is when it will slow things down. I find the most resource hungry anti virus programs to be Norton and MaCafee.

What effect does avg antivirus have on the performance of a computer system?aurora

Very little.

What effect does avg antivirus have on the performance of a computer system?download

I have AVG free and i find it has less effect than other sysy=tems such as Macafee or norton. It does run some programs in the background to constantly monitor the system.
what effect does avg antivirus have on the performance of a computer system - it fools you into believing you are protected from virus when in fact AVG has a very poor detection rate (only 82%) as free AV goes its at the bottom end there are far better free AV's out there which do a better job, here are two both have better detection rates than AVG:

http://www.free-av.com/antivirus/allinon...

http://www.avast.com/eng/download-avast-...
it tends to keep it clean without slowing it down....simple really.
It only takes up about 30mb of RAM, so nothing really!
Yes, AVG will cause some performance degrade. The software must constantly update it files and signatures. All this information is logged in your computer. The majority of the information is placed in your registry.