Rapid Memory consumption when adjusting slider value for Blueprint in Details Panel

When a Planar Reflection component has been added to a Blueprint that has adjustable sliders that can be edited via the Details panel that updates the Blueprint via the construction script the memory usage can climb dramatically within a few minutes, however it will reduce back down over time. The issue here may be with anyone with lower amounts of memory could crash the editor/video driver, but I was unable to reproduce that with 32GB of RAM.

Originally reported as a Planar Reflections issue. I think using the Planar Reflections may show the consumption more rapidly, but the issue happens without them specifically.

Notes:
Watching the memory usage it will go back down slowly on its own after a few moments. If you PIE it seems like there is some clean up that happens and reduces the memory usage back to ~1.5-2GB.

Using the First Person Template project as an example:

• Project loads with Planar Reflections activated with mem usage ~800mb.
• Adding the PR to the SkySphere and adjusting the sliders it will increase the mem usage. I did this to ~7GB.
• Leaving the editor view by itself the mem usage dropped back to ~1.8GB a minute later.
• Going to a new level/PIE reduced mem usage to ~1.5GB instantly.

Tested with:
4.12 Release Preview 3 CL-2970308
Dev-Main 4.13 CL-2973886
4.13.2 - 3172292
4.14.3 - 3249277
4.15.2 - 3416026
4.16 preview 2 - 3415565

Original Repro Steps
1. Open UE4
2. In the Default Scene select the SkySphere BP
3. Open the Windows Task Manager and take note of the Unreal Engine project memory usage
4. In the Details Panel for the SkySphere BP adjust the slider values rapidly back and forth without letting go. Do this multiple times for a few moments.

Alternative Steps (Most Recent)
1. Open attached project.
2. Open the BP_PlanarReflection and select the Static Mesh plane.
3. Begin rotating the plane within the viewport (do not compile or save as this seems to free up the memory)

Results: When adjusting the slider value in the Details panel for the BP the memory usage will jump climb in MB usage each time.

Expected: The memory usage should not be as drastic in consumption

Memory Leak in 4.15 when using planar reflection component

Memory Leak in 4.15 when using planar reflection component

4.12p3 Extreme Editor Performance/Memory Issue w/ Planar Reflections