My FPS for my computer becomes incredibly choppy when I first tab out of WoW specifically to Chrome. The FPS remains choppy until i click on a 2nd window outside of the game after alt tabbing then returns to normal. This only happens in WoW as other games do not have this issue at all, I can replicate this issue at any time and as I said it fixes itself by simply selecting clicking on a 2nd window outside of WoW after tabbing to Chrome.
I looked over this and am sorry to hear the troubles you are having. I hope to help out here and get things working.
The first thought I have here is to go in to the system setting from the game menu, from there go to advanced and uncheck background FPS. See if this helps.
If not, try placing the game into Windows mode. Sometimes full screen mode can make it act strange when alt tabbing.
Last, try turning off any overlays like Discord or Overwolf that may be in use.
If nothing here helps, I would want to get a DxDiag from you.
DxDiag instructions (click to expand)
Press Windows Key + R.
Type DxDiag and then press Enter.
In the DxDiag window, click Save All Information.
Name the file something you can remember and click Save.
To add it to your reply here:
Open the text file and copy all of the text.
Paste the text in your reply.
Highlight all of the text and click </> on the post editor.
Note: If your DxDiag does not fit in one message, you can break it up into two posts, or post it on Pastebin and provide the numbers/letters after the .com in your reply.