This benchmark was performed by duplicating 50 real-world markers equally, then to distribute the markers throughout the map, their coordinates were chosen at random from the map's bounding box. The frame rate was determined using Chrome's built-in FPS meter while crudely moving around in the map. Throttling was handled through Chrome's built-in CPU throttling mechanism.

CPU: Intel Core i5-8265U @ 1.60GHz
OS: Windows 11 (in "Best performance" mode)

I would use a maximum of 2,500 markers for faster machines and 1,250 markers for slower machines.

Additional notes:

• Note there is no need to guarantee a smooth frame rate (that would be anything close to 60 FPS). What matters is how it feels. 15 FPS start to feel like a stop motion animation, but are still very much acceptable for our use case.
• A limit of 1000 points sounds like a good starting point.
• To collect that many points you have to move and zoom the map 50 to 100 times.
• Maybe we don't need to do anything. When the user notices a slowdown, all they need to do is to disable the nearby feature.