Figured this may be the best forum for this topic.  I recently loaded FSX steam and I am beginning again from a long hiatus and I am out of the loop on a lot of things obviously.  Right now I am just running the standard version and have not yet attempted to download and install any types of add-ons yet.  My question is when I do begin that process is it best to totally deactivate AVG free version as I download and install new additions to the program?  And when that process is done and I reactivate AVG will it interfere with the FSX program running properly?  

Although I don't use AVG (I use Bitdefender), I've never had a problem downloading files with the antivirus enabled. That's what it's there for, after all - to catch any suspect files from the Internet. Call me paranoid, but legitimate web sites have been compromised in the past and I don't think it's worth the risk downloading anything from the Internet without active protection. To see how the different antivirus programs affect performance, see http://www.av-comparatives.org/wp-content/uploads/2017/06/avc_per_201705_en.pdf for the latest comparative tests (May 17). Some programs are much better than other when it comes to how they affect performance. FSX Steam Edition normally connects to Steam each time you run the sim, so unless you decide to run in offline mode, I'd say keep the antivirus running to be sure you're safe. I see no noticeable performance difference in FSX with my antivirus running.

With AVG if you are downloading from a known trusted source you can "abort" it. So it will stop doing a check.

19 hours ago, vololiberista said:

With AVG if you are downloading from a known trusted source you can "abort" it. So it will stop doing a check.

But why would you want to? As I said in my earlier post, plenty of trusted sites have been compromised in the past and the antivirus software shouldn't affect the download speed at all, it normally just checks the file once it's downloaded. Better safe than sorry.

Thank you so much for the input guys!

18 hours ago, vortex681 said:

But why would you want to? As I said in my earlier post, plenty of trusted sites have been compromised in the past and the antivirus software shouldn't affect the download speed at all, it normally just checks the file once it's downloaded. Better safe than sorry.

Let's say that I know that a beta update for PF3 issued only to the beta testers is going to be secure!!!!

AVG therefore gives me the option to choose.