Particles needsReset performance issue

I was doing Qt6 dev profiling yesterday and bumped into https://codereview.qt-project.org/c/qt/qtdeclarative/+/301377

Noticed that QQuickParticleAffector::postAffect inserting data into needsReset is slow. And the reason is that QFlatSet insert uses std::find to prevent duplicates, which drags the perf down when the amount of particles increases.

Attached a simple example application which allows increasing the particles amount and seeing a simple fps counter, use better profiling if needed. Same can be seen with other particles examples as long as they have more particles and at least one affector.

The results I get on Galaxy Tab A7:

particles | QFlatSet | QSet
5000        34 fps     60 fps
10000       9 fps      38 fps
15000       4 fps      28 fps 

So when the amount of particles grows, QSet performs up to ~7 x better.

Are there examples & hardware where QFlatSet in this place performs notably better? If not, should we switch back to QSet at least on Qt 6 dev? Or do some better optimization here?