I have encountered folk cringing in fear of uninstalling an antivirus "Won't I be unprotected?" to install the next. Sorry folk but if you want to risk it all, install more than one AV.
As to speed, I often find it's something. But that something is almost never the antivirus (unless it's McAfee or Norton.) Then we have overreaching AV suites that plug into the browser or do BOOT TIME SCANS. Hey, those are your choices. But to maintain the highest level of security you pay with long boot times and slower operation overall.
About AVG. If this was mine I'd remove all antivirus then hit NINITE.COM for AVG. Here's why.
Backstory: Ok so I am not particularly adept when it comes to computers. About 2 weeks ago, I got an adware virus. I got rid of it, but I decided to install Panda antivirus, because I read that it was more comprehensive than the AVG I had installed. I uninstalled AVG, and the computer went into safe mode and I was quite scared for my computer. In the end, I came out fine, with Panda as my new antivirus. Eventually I downloaded windows 10 and had no troubles for the first week. Now, my startup time is extremely long and my computer's speed has massively dropped. I can't seem to open Panda either. Norton seems to have been thrust upon me by windows, but I have denied it because I have panda. The speed has gone so downhill that it now takes about 2 minutes to just open up notepad. I eliminated some old startup programs, but it didn't help. Even after I start my computer, the speed is horrendous. Many programs just won't open sometimes either. Chrome will either take a minute to open or just not open. Would it be safe to download AVG even though Panda is still active? I'm hesitant to uninstall Panda for fear of what happened last time, and since I can't seem to do anything with it, I want to go back to AVG. My laptop where this is happening is a 2 year old Toshiba Satellite C-55-a model with a 64 bit processor and 8 gbs of ram. I'm not quite sure if the drop in speed is due to a virus. What do you think I should do?