Had anyone using Mcafee Anti-Virus software?  

i used before is good, your security level try not to lock it too high, it might slow down your server.

All virus checkers can be set to update and scan your computer automatically at set times. The updating will make your internet connection seem slow and the scan for viruses on your computer will make the computer seem slow.

If you have a slow connection to the net it is better to change the setting so that you decide when to update when it is convenient for you. Like, leave it updating while you have lunch.

I used to use this too, AOL (my ISP) recommended it and charged me £2.50 to use it each month! However I didn't think it was all that and now use AVG as it's free and reliable!

I had Mcafee Anti Virus installed on my last computer that I had. I honestly didn't notice if my speed changed at all.

Mcafee Antivirus is a good antivirus i think because i used it and i never had problem with it, but it is burden my PC resources and like yours, sometime it makes my pc slower. So i decide to change to avast. It's free antivirus and very good antivirus like mcafee, the difference for me is avast use resources much less than mcafee does.

Its not a secret that mcafee makes your laptop slower, you can uninstall it then install other antivirus, i recomend avira and karspersky. It uses few of your RAM memory

Yes, while is getting updated, we can not do any thing, if we have large volume of RAM,.Even, we will not be able to close the windows, will torture us a lot. Also while scanning, the system will become too slow, but not as like it become updating. Only because of this reason, I uninstalled the software and I installed the Norton. I don't know, why these software manufacturers are not keeping this in mind and the anti virus software should not affect the performance of the system in any way. But here, it blocks all other.If we see the CPU usage,the more will be from this software.

People said McAfee is a resource hog, Not really.
It's not the best at detecting. But when cleaning, It works! McAfee Saved me from Polymorphic viruses. Well, It's still your selection..If you want free complete security, I recommend COMODO Internet Security

I am also using McAfee anti virus.I had also used Kaspersky but I really don't like it.I prefer McAfee more since it has got this site advisor thing which I think is important.I don't find any difference in speed except when it is running on the background checking my PC, then it gets little slow.Good day!

I am also a user of Mcafee one but now i simply hate it because i also had same problem as you have so now i am using "AntiVir" anti virus i have no problem with this software it is capable of detecting all types of virus and it is not making PC slow so i suggest you go for this anti virus.