What we see is all there is in the scene right now? If I had poor perfomance just with that I would be looking for some specific cause or problem that causes the lag, because in my experience that scene shouldn't have bad performance so I think something is wrong with it.
You had problems with masked gradients previously, which is a known bug in the latest versions. Does this scene have gradients or any other masked effect?
Color points (I don't remember if masked or not) had a problem that affected performance too. It was improved for the latest version but it's not totally solved so I would avoid them.
Aside from those two, negative keyframes and the corrupted references I mentioned to you here (
viewtopic.php?p=218662#p218662) I haven't seen any other bugs that affect performance so far.
When I had performance problems and made a little investigation about the different Moho features and their impact, bones were surprisingly performant: adding or deleting 30 of them barely had an impact on the performance of the project. Bones only had a serious impact when combined with the masked gradient bug, and just one bone was enough to cause the bug and affect performance.
Try a similar approach. Make a copy of your project and play with it, delete things one by one and see the impact. You can measure perfomance in different ways. The time to copy-paste keyframes is a good indicator of editing performance, while the FPS playing the scene in the workspace is a good indicator of rendering performance. Each one can be affected separately by different things, so is good to know what kind of bad performance you actually have.
If you want to share the file, I can take a look at it.