Could I point out that a week ago the US Technical Support forum acknowledged that these freezes are due to an issue between the interaction of Diablo III’s sound system and Windows 10 version 2004 and the developers are working on a fix…
https://us.forums.blizzard.com/en/d3/t/main-thread-windows-19041-freezing-for-5-10-seconds/18380/87 (7 days ago)
We’ve synced with the devs and it looks like we’ve got enough reports now. Thanks for answering the call to action and getting us those DXDiags/Error reports. I’m editing the other messages to indicate that we no longer need more data. You are welcome to continue reporting issues or work arounds that you discover, but you can save yourself some time and stop gathering the previously requested logs now.
The devs are aware and looking into the issue now. We’ll let you know as we get more insight into the problem, but for now, there are some work arounds posted in this thread. The most successful options currently are temporarily disabling sound outputs on your PC. This will result in playing without sound however. The other option is to roll back to the previous build of Windows 10 while we work on this.
https://us.forums.blizzard.com/en/d3/t/main-thread-windows-19041-freezing-for-5-10-seconds/18380/97 (4 days ago)
Our team is still investigating the issue and they believe they found the source of whats been causing the issue. It’s a frustrating issue and these types of compatibility issues can take a bit of time to resolve.
Our team needs to run through testing and replicating the issue to find the cause, then work on a fix for the issue. Once a fix is in place, our QA and compatibility teams need to make sure the fix works. If they can test and verify the fix in place works, an update or hotfix will be pushed to the live servers. It can be a lengthy process, but we want to make sure the fix in place does resolve the issue before it’s pushed out.
Since a lot of replicating and testing needs to be done, it’s difficult to give an exact time frame at this time. We’ll communicate any new information or updates on this forum thread when our team has more details to share with us. Thank you for all the provided details so far, it’s greatly appreciated and helpful!
There are temporary work-arounds in the thread which require replacing a .DLL file, running Diablo III without using the Battlenet launcher (because otherwise it would repair the replaced .DLL file first) and playing Diablo III without sound.
So, if you recently updated to Windows 10 version 2004, that’s much more likely to be the cause than anything to do with your firewall. You can check which version you’re on by typing WINVER into the search bar and running the command.