Performance Drop Occurring During PIE When Blueprint is Open

Having a blueprint open during PIE causes a significant drop in performance. Having multiple blueprints open can almost render more complicated projects unplayable.

The user has reported 120 fps with no blueprints open, and a drop to 60 with just one blueprint.

Found in 4.12 Preview 4. Reproduced in 4.11.2 binary and Main CL 2980216

1. Open the editor (Third Person Project)
2. Open the Third Person Character BP and place it on the second monitor
3. PIE
4. Open the console and type 'stat fps' to show the fps (Observe the framerate)
5. Close the Third Person Character BP

Result: Having the blueprint open causes a significant drop in framerate, reducing it by almost 50%.

Expected: The framerate would remain consistent with the blueprint open.

Open vs closed blueprint affects character control

Severe performance drop for PIE when blueprint editor windows are open