Level Sequence option "Allow Level Edits Only" causes Frame Rate drop when used

When using the new option "Allow Level Edits Only" there is a drastic frame rate drop while playing the sequencer. This frame rate drops when only using this option.

Versions Tested:
4.16.3 - CL: 3561208 - Unable to reproduce (Feature not added at this point)
4.17. - CL: 3573198 - Issue occurs
4.18 - CL: 3585944 - Issue Occurs

Regression:
This issue is not a regression, as the feature is not present in 4.16

1. Create a new project (No Template but allow starter content)
2. Use the console command "stat fps"
3. Create a new level sequence > Name it "TestLS" > open The Sequence
4. Click the Properties (The pencil icon located next to the magnet)
5. Select the option "Allow Level edits only"
6. Add a new camera (Use the Camera Button on the top hot bar)
7. Set 2 Keyframes > One keyframe at 0 and another at 150
8. Click the play button
   Result: The frame rate drastically drops while the camera is playing
   Expected: The frame rate does not drop drastically