Editor FPS has significant drop when moving a BSP brush in level with multiple BSPs

Editor performance plummets when moving BSP brushes in a level with several other BSP brushes present. Navmesh regeneration is the main cause as the full bounds for all BSP are used to determine which tiles to dirty. This results in large chunks of navmesh needing to be regenerated. In a basic test level with 20 BSP brushes (all picked from the Geometry tab from Place Actors), I have slowdowns to ~8 FPS when moving a single brush in the level on my dev machine. Framerate from the associated licensee appears to be ~5 FPS.

Here is a screenshot of the editor showing the FPS and all tiles within bounds being dirtied:

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Steps to Reproduce

1. Create a level of some complexity using BSP. It does not need to be a massive world - a small blockout with a few rooms will suffice.
2. Attempt to move any BSP brush with the transform gizmo in the viewport.
3. Observe performance absolutely tank as you drag the brush around.