Events sending beatmap cause main thread to freeze on songs with large thumbnails

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Starting, pausing, and resuming maps for beatmaps with large thumbnails results in a significant lag spike. Reportedly, an example of such a map is buck wild, with a 2500x2500 cover image.

This is most likely due to serialization of the beatmap.songCover property needing to escape the whole string every time.

Potential solutions

1. Finally make use of the GameStatus object by creating a pool capable of creating a copy of the master on demand, and move JSON serialization off the main thread.
2. Rescale the cover image to a maximum resolution. This could be a setting in case someone wants the highest resolution possible.
3. Create a variant of the JSONString class which would cache the escaped string to prevent performing this task multiple times.

Environment

HTTP Status version: v1.19.1 and below