This may be unrelated but I had some users report very high CPU usage starting with late 10.15 versions when I draw text using CALayer on retina. The bug doesn't happen on every single machine, I can't reproduce it on my Late 2015 iMac for example. I ended up adding a switch in my screensaver (Aerial) for high resolution text because of that. To directly answer your question, the way I fixed it is by rasterizing the layer I'm drawing, using this : nLayer.shouldRasterize = true https://developer.apple.com/documentation/quartzcore/calayer/1410905-shouldrasterize Do you see the high CPU usage in app mode too ? You may be able to file a feedback so they can track this down, as it's a huge regression and I still to this day have no idea exactly why it doesn't affect everyone.

Same issue as Jakub, I would add ScreenSaver settings to that list too if possible. @RudoBaker did you report the feedback yet ?

@DTS Engineer Hi, we managed wtih @XMI to narrow down the issues a bit more, here are 3 feedback numbers to put on your radar if you can. Also, the Screen Saver category is no longer in the Feedback app, so I had to file to what felt closer (System Settings > Screen Saver). Hopefully that's fine. If that's not the case and I need to refile, please let me know, as I don't want those to get ignored because of this. FB19201567 - System Settings spawns duplicate legacyScreenSaver.appex instances with improper lifecycle management This is an expanded version of the isPreview issue with as much details as we gathered since. FB19204084 - Screen Saver accumulates instances of ScreenSaverView over time without stopping them This one is a major bug that was introduced in Sonoma with the arrival (I believe) of WallpaperAgent. Contains as much information as I could add, this one is pretty major because 3rd party screen savers are no longer stopped and keep running all the time (unless we do a very naughty workaround), and get stacked over time, causing a lot of CPU/GPU/RAM load FB19206021 - Screensaver will not display on secondary monitor in some circumstances This is a new bug in macOS Tahoe, screensavers will not display on the secondary monitor if at least one of them is a third party. Happens also if the screensaver set on the secondary monitor is a first party one. Yet it's linked to legacyScreenSaver.appex too. There's a reproduction sample linked in each, based on a simple template I maintain to create a screen saver in Swift (there's still no template for this in Xcode!) : https://github.com/AerialScreensaver/ScreenSaverMinimal We have (pretty bad) workarounds for the first two and there are switches in the settings to enable them (they are disabled by default). We can't workaround the 3rd one (though the sample makes it very easy to reproduce, I give information about this in the radar). Hopefully that helps, we spend a lot of time on this. Thanks for looking at our niche world of screensavers !

[quote='851294022, DTS Engineer, /thread/787444?answerId=851294022#851294022'] Thank you. I took a quick look and some of them were off in the weeds. I’ve taken steps to get them back on the right path. [/quote] Many many thanks for this! I noticed the first bug was somehow assigned to me, I'm not sure what I did wrong there. In any case, thanks for your help! If you haven’t already done so, I’d appreciate you filing an ER for a modern appex-based screen saver API. And if you do file a bug, please post your bug number, just for the record. I did in 2019 as soon as it was introduced FB6363533 but that was probably not my best feedback. I tried to do it properly this time with FB19235887, hopefully I didn't ramble too much... I wanted to provide as clear a picture of the situation that I could, and the rationale for change. I'm not a native speaker however so hopefully it still makes sense. Again thanks for taking the time to look at all this!

@DTS Engineer FYI posted another FB with an issue reported by users when I compile the screen saver with the SDK from Xcode 26 beta4 and beta5 : FB19580645 It's a backward compability issue that's likely only tangentially related to screen saver, I narrowed it down to a crash with trying to call an unavailable hidden SDK function when opening a XIB with a scrollview. Opening the XIB crash on Sequoia and all previous versions of macOS : FAULT: NSInvalidUnarchiveOperationException: <private>; (user info absent) Could not instantiate class named _TtCC6AppKit14NSScrollPocketP33_EC3F85FAB7755D56E669206D2B17725B12BackdropView because no class named _TtCC6AppKit14NSScrollPocketP33_EC3F85FAB7755D56E669206D2B17725B12BackdropView was found; the class needs to be defined in source code or linked in from a library (ensure the class is part of the correct target) (log above is on Sequoia) The bug appeared in with the SDK of Xcode 26 beta4 as far as I can tell and is still there today with the SDK of Xcode 26 beta5. If you can make sure it goes to the right team, as I couldn't find a fitting category to file it in! Take care

FYI No change in beta7 to reported bugs.

@DTS Engineer Updated to RC and sadly, no changes on the big screensaver bugs. FB19204084 is by far the worst. Our workaround for it is imperfect and I had reports from users where in some circumstances, "something" gets messed up and after that macOS will just refuse to try to launch the 3rd party screensaver (giving users a black screen). Only fix in those scenarios is to restart macOS, which is the worse thing I can tell a mac user to do.

@DTS Engineer any chance you have an update for us ? Running latest 26.1b3 and no change to report yet. Thanks !