[phil294]

It's definitely a website bug, as goes from 1 FPS to smooth if you go to S+U and back to U again. (debugger didn't help, but it's all minified anyway)

[riggsdk]

The slowness in firefox comes from the station name drawing. Going from U to S+U and back again seems to reset the setting for drawing them. The settings option for drawing the station names is somewhat buggy.

To optimize this the text should probably be drawn to another canvas/surface and layered behind the main one and not be updated that often.