The current engine version (4.22) seems to suffer a huge performance hit when using the demo recording (demorec) feature. This issue is present in both the editor and the packaged game (developer builds). This is a regression from 4.21.2 (CL-4753647) where there was no change in FPS. From a Blank project the FPS drops from 120 to 30. In a Third Person project it drops from 120 to 15.
This was reported and tested in 4.22.2 (CL-6574378) and reproduced in 4.23 (CL-6810573)
1. Open the UE4 Editor and create a Blank or Third Person Template project
2. Close the project. In it's Config/DefaultEngine.ini add the following lines and then reopen the project:
3. Play in Ediotr and use "demorec" from the console. Observe the FPS. Then demostop
Results: There is a significant difference in performance (FPS) while recording a demo
Expected: No fps drop when recording a demo
There's no existing public thread on this issue, so head over toAnswerHub just mention UE-75528 in the post.