Low framerate in editor with many tracks

[t0stiman]

When you have lots of tracks in the Railway scene, the framerate of the Unity Editor 'Scene' window drops so much that the window isn't really useable anymore. For example, on my test map, the framerate drops from 220 to 3 FPS when I load the Railway scene.

@WhistleWiz said on Discord:

About the track drawing, I tried implementing a certain optimisation, but unfortunately it seems the lines themselves are to blame. You'd need to change the library itself. I recommend disabling each yard after being done with it, just so they don't hog performance.
As for the rest, I already added a tool that can merge multiple tracks into a single one, which improves performance a bit. The game uses a single track object for everything between 2 switches basically.