Increasing the spawn rate of a CPU particle sim will cause a memory leak in the vertex buffer. 

Steps to Reproduce
  1. Create a Niagara emitter based on the fountain preset
  2. Create a system with the newly created emitter
  3. Add the system to a level
  4. Use stat rhi to track vertex buffer memory usage
  5. Increase the emitter spawn rate to ten times the current value
  6. Watch the vertex buffer memory increase.
  7. Decrease the spawn rate to the original amount
  8. Close the Niagara editor, and delete the system from the level

The vertex buffer memory usage will not recover from the spike after increasing the spawn rate, even after closing the Niagara editor and deleting the system.

Memory usage from the increases particle count should recover when the number of particles are reduced, and the systems are deleted/closed. GPU sims behave in the expected way.

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ComponentRendering - Niagara
Affects Versions4.224.23
Target Fix4.23
Fix Commit8360499
Main Commit8484875
Release Commit8360499
CreatedJul 16, 2019
ResolvedAug 29, 2019
UpdatedFeb 13, 2020