This is cached in Render, and gets cleared along with render pass GPU
textures when there is no editor open using it, or a new final render is
started.
The context and texture pool are cached. But the evaluator is re-created
every time as this only runs on compositing node changes, which require
recreating it anyway (unlike the viewport where e.g. camera navigation
does not need a new evaluator).
Pull Request: https://projects.blender.org/blender/blender/pulls/108909
711fb3e386