2017.3 Editor overhead performance degradation ?

That does not sound right. Can you please file a bug report through the bug reporter tool found in the help menu? I'd like to have a look at that but I'd need a repro project. In general we should have improved the performance of the Profiler window in 2018.3.

Also did disabling the UI Profiler module work?
Generally speaking, the different modules can have overhead that would vary from project to project. So far, I was aware that Audio module, especially in detailed mode, has a higher overhead on the collection side. GPU is disabled by default because it currently has a heavy impact on the players performance too.
If any module, or the Profiler in general, has a performance regression, we'd want to know about it.
Also, In 2018.2 I've added a performance test for the UI of the CPU Module to prevent regressions, it might not catch everything and we need more of these, also for the other modules. A bug report can help to push for more of these too.

 

Also, in 2018.3, we've added the performance improvement that modules that have been disabled in the UI do not collect data in the player. Previously that was only true for the GPU module.

 

There is currently a bug with the "Other" category where time that falls under this category will not be shown in the CPU modules frame time chart, unless samples that contribute to that category are selected. Such samples are e.g. the Editor Overhead, i.e. the fact that if you're running the game in Playmode in the editor, both the player and the editor run in the main thread and that that impacts the framerate if the entire editor and player frame. Additionally, there is a bug where a soft VSync (WaitForTargetFPS, the only VSync the Editor has) is falsely attributed to other due to the newly added WaitForSemaphore sample that was supposed to indicate that the CPU is idle for that time frame.
For more reliable info about where time is spent, please check the Timeline view until those bugs are resolved.

 

CC @alexquare :
Can you two please deep profile this with profile editor and check if whatever is happening in sceneview or any other tooling that updates alongside sceneview is causing this? Then, if this is related to Unity code, please file a bug report for it?

What does the profiler say, when you enable Profile Editor, eventually also Deep Profiling?
Also, this could be related to a bug in 2019.x (that has since been fixed) where the the sceneview got rendered twice. supposedly that didn't happen in your version but if you profile it and the profiler tells you otherwise, please file a bug

Please profile the Editor Overhead by swtiching on "Profile Editor" and depending on the results from that, please do file a bug for that, as well as one for the Audio manager.

 

Could you please profile that with the new memory profiler package as well? There you could use the diff functionality to find leaking mesh data issues. If you find an issue that seems to stem from Unity, please file a bug for it. If you have trouble finding it in there but it still being visible in the Memory profiler module of the Profiler window, please let me know and also file a bug for that against the memory profiler.

 

@wood333
The only thing that might explain some of this that comes to mind, is that the UI Details Profiler, when selected, at some point cause the Profiler Window to repaint every frame instead of every 5 frames (as it usually does). That repainting has been fixed but I'm not sure when exactly.

Besides that, It's an unknown issue to me and I'd appreciate a bug report with a small repro project

 

Well, I'd expect it should be limited to some uGUI UI setup. Maybe that is separatable? If it's intermittently, that makes it a bit trickier obviously... :/