Add additional GC related benchmark

Given this performance regression in Python 3.14, it would be nice if we had a benchmark which would have more clearly shown it before final release. I have a new GC specific benchmark but it doesn't do things that would show this regression.

We should consider adding a new benchmark. The key features would be:

• creating a bunch of net new container objects, in order to trigger many, potentially young generation, collections
• creating tuple objects that can be untracked by the GC, in order to avoid slowing down full collections

Ideally we prefer to avoid a micro or synthetic benchmark and instead find some kind of real application that shows this regression. E.g. near the 3.13 release, we found a GC regression shown by Sphinx building Python docs. Something like that would be good.

Lisez d’abord la régression de performance liée de Python 3.14 et le benchmark existant spécifique au GC dans la pull request 381. Étudiez un benchmark d’application réelle, plutôt qu’un microbenchmark synthétique, qui crée de nombreux nouveaux objets conteneurs et des tuples non traçables et met en évidence la régression ; le travail sera considéré comme terminé lorsque le benchmark montrera clairement ce comportement avant la release.