Doesn't memory keep growing?

**Describe the bug**
https://github.com/EmbarkStudios/puffin/pull/169

I get that it's PR for optimisation.
But doesn't this result in an infinite number of ScopeCollections and thus an ever-increasing memory footprint?
In fact, if you try running the current puffin_http example server, the memory keeps growing over time.

I'm just checking because after applying the release with this update, the memory exploded.

**To Reproduce**
cd puffin_http
cargo run --example server

**Expected behavior**
Memory should not continue to grow.