Since the 8/14 patch I've consistently run into an issue where my fps will drop to ~ 1 frame / 5 seconds. Inputs still register properly, if I hold forward I will move forward for the distance you would expect but with significant visual delay on everything but my cursor. This same behavior persists to my desktop after exiting the game and a reboot is required.
I cannot determine what causes this. I can sometimes sit happily in a bustling Orgrimmar without issue but it will start up mid flight path to Azshara. I can be doing normal bank management in Thunder Bluff for 10-15 minutes when it starts again while walking to the AH. I even had a group wait for me to painfully walk into Blackrock Spire, log off, reboot, and rejoin only to have it happen 5 minutes later.
I have tried disabling all add-ons and the issue persists through multiple clean installations through both the full client download and the launcher. I recreated the issue today with a clean unmodified install.
I tried stress testing my computer with other online games with higher system requirements such as Counter-Strike 2 and Battlefield 6 but could not recreate the issue.
Please let me know of any other information I can provide that would be helpful.