I've been using Bitdefender 2014 Total Security for the last year now and I've been pretty happy with it. My subscription is up for renewal shortly and I got an email the other day from Bitdefender advertising their new Total Security 2015 and a discounted offer for me to upgrade.

Being a pretty satisfied customer of the 2014 suite I took them up on the offer and upgraded. To my chagrin I found my framerates in FSX took a hit. Whereas I could sit in a light GA at my local aiport (Orbx England scenery) and easily maintain my 30fps lock, I was now getting fluctuations between 14 and 25 fps and very stuttery in the air. I added an exclusion for my FSX folder and fsx.exe in the antivirus but to no avail. I confirmed the problem by disabling the real time scanning and my framerates went back to normal.

What's more I was having a problem with World of Tanks where upon launching the programme it would minimise to the taskbar and wouldn't allow me to maximise it again. I tracked this down to Bitdefender's Autopilot feature which automatically configures the security to match what you are doing with your computer. When launching WoT it would go to "game mode" and would somehow take the window focus away from WoT and wouldn't give it back.

Luckily Bitdefender have a 30 day refund policy, so I'm taking them up on that. I've heard good things about NOD32 Antivirus which apparently is pretty good and has an extremely light footprint, so I'm running the 30 day trial to see how I get on with it.

Funnily enough last year when I was looking for a new AV programme I found Avast massacred my FSX framerate, but Bitdefender was fine, and that's how I ended up using the latter.

So moral of the story is be careful with antivirus programmes and FSX performance. From what I've read if you've got a beefy FSX installation with lots of stuff installed the huge number of files the programme calls (scenery, textures, etc etc) can get the attention of the heuristics on antivirus programmes and cause things to slow down.

You can normally set your AV to ignore certain folders or even whole drives.

I use AVG and have no issues.