Irregular rhythm of blinkers

Hello, I'd like to ask you guys, if anyone else has noticed that the rhythm of the blinkers in OMSI buses is a little bit irregular?

Every couple of »blinks« there is one that flashes faster. This can be heard and seen via the green control light on the dash and on the actual blinkers on the bus.
I thought that this is caused by the game performing slowly, but even if I go to a small map like Grundorf, where I get over 40 FPS, it is the same.

Is there something I can change in a config file somewhere to resolve this problem?

Thank you.