(UE-4.6 only) Extreme editor lag and mouse jitter while persona is undocked
Starting with brand new project, I got up to step 4 (Intro to Persona) of the Getting Started: Introduction to Blueprint 3rd Person Game Creation" tutorial when both the UE editor's viewport and all UI elements started lagging badly.
I turned all the performance options down and restarted UE4. After restarting, UE4 ran as smooth as glass (about 60 FPS) until I double clicked on the "Idle" animation in the content browser (which opens the Persona tool in a new window per tutorial step 4), at which point the UI lag and mouse jitter returned.
After playing around, I found that docking the Persona window made the problem instantly disappeared (back up to about 45 FPS).
I started with a clean project (per the tutorial), but if you can't reproduce this easily, I'll erase my preferences and take it step by step to see what else might be involved.
Note: I said this was UE-4.6 only because I use multiple monitors and I've never seen a problem with undocked windows until now, BUT, I've also never used Persona until now so this COULD be present in older versions as well.
It is expected behavior to see a frame rate drop when you have the editor in the background and an a separate Persona window floating in the foreground as your gpu has to render the contents of both windows. Docking the window and seeing the increase back to only 45fps is expected as the animation is being rendered in real time in the Persona window.
However, when you switch tabs to bring editor back to the foreground and the Persona window is running in the background, the frame rate should return to around 60fps. When reproducing your issue I found this was not the case in either the OS X or Windows environment. Subsequently I've entered the following report [UE-6354].
When this issue is addressed in a future build an update will be added to this post. Thank you for bringing this issue to our attention.
answered Dec 05 '14 at 10:13 PM
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