bevy memory usage grows over time

## Bevy version

0.8

## What went wrong

I left a bevy app running in the background for a long time, and well, it grew to 12 GB memory usage over the course of ~8 hours.
The App is just a few planes and a simple controller system.


It seems that a bevy app just with the default plugins and nothing else also grows over time, so it's not my code but a bevy problem.

The issue names no files, entry points, or tests. Start by reproducing the reported memory growth with Bevy 0.8, first using only the default plugins and then the minimal plane application, while measuring usage over time. Done means identifying the source of the growth and confirming that memory remains stable after the fix.

Written by the indexing model from the issue text.