Solved

Switch league ornot

Hi I'm in a semi-uncompetitive rookie league, which I'm dominating. Should switch leagues to an active league now, at the end of the season or some other time?

Switch ASAP, being in "inactive" leagues is not going to make you faster, look for a competitive and good environment league that you can compete and get experience. And on a good time for you to be able to watch the races
I was in the same position when I started playing the game but realized that if I kept racing inactive managers I wouldn't learn anything from it and it wasn't fun at all to just dominate bots...

The important thing is not when you leave your current league but the point in the season at which you join another league.

Find a league you want to join, PM the league host so that he/she knows you're a serious active racer and then join after they complete their last race of the season (Abu Dhabi).

If you're an active manager and the league you wish to enter is fully subscribed, most decent hosts will kick an inactive team to allow you to join.

Moved to formula zero now so this is resolved

Have fun!