Disable sync icon animation

[felixwrt]

During my investigation of #4918, I found that the animation of the blue sync icon in the tray causes massive slowdowns when the tray is open. I don't know exactly why this is happening, but I suspect that there's a scheduling issue between running the animation and performing network IO. Both tasks could be running on the same thread and blocking each other or something like that. Unfortunately, I don't have enough knowledge about Qt and this codebase to find the root cause and fix the problem there.

Since the performance bug is pretty severe, I'd like to propose a quick fix instead: Simply turning off the animation. With this single line change, the icon won't be spinning anymore, but file transfers will be a lot faster. IMO, performance beats aesthetics in this case.

Let me know if this would be an option for you. Thanks in advance!

[nextcloud-desktop-bot]

AppImage file: nextcloud-PR-5941-9a4ca0ae4945bbc64735cb9b2e657f0c9562e887-x86_64.AppImage

To test this change/fix you can simply download above AppImage file and test it.

Please make sure to quit your existing Nextcloud app and backup your data.

[claucambra]

I agree that functionality > aesthetics in this case but, IMO, this is not a real solution. There are ways to get this animation running without blocking/impeding the rest of the app

Still, thanks for surfacing this -- curious that the simple sync animation can wreak this much havoc. Will investigate a bit more

[PhilippSchlesinger]

@claucambra While this is not a real solution, it could work around a serious performance problem in the nextcloud client.
I would suggest to applying this quick fix until a real solution to the root problem is found.

[PhilippSchlesinger]

@claucambra, @felixwrt:
As this is a long-lasting issue with a severe impact on the performance of Nextcloud Client, could you both maybe share some hints which code paths are affected by the change introduced in this PR, maybe even in the original issue #4918 so more pleople could help tracking down the root cause.

[felixwrt]

I know next to nothing about the Nextcloud client implementation in general and Qt in particular. I would suspect that NC uses Qt incorrectly which causes the slowdown. I could imagine that the animation and the file transfer handlich are running on the same thread and are blocking each other from making progress, but that's only a theory. I tried to find the root cause before opening the PR, but didn't succeed. I can't be more helpful, sry.

[felixwrt]

Closing this as an equivalent fix was done in #6691