Engine cranks slowly when hot... but starts

[Dino86]

I have an issue with my AE86.

Car starts when Engine is cold.
When Engine is hot, the starter motor cranks very slowly (Engine revolution is maybe 1 per 2 sec or so... really slooooow)... but it always fires up.
It feels like after one rev, out of nothing it starts... It's quite impressive

Since it always starts even with low starting revs engine is fine I would say.

That leaves me with several options only:

Battery: I don't think so since it doesn't become worse with all lights on (incuding added lamp-pod)... still I can start the car and the lights don't dim that much.
Starter
Cables I added extra ground cable from Gearbox to chassis but almost no change
Ignition advance: I find on the web that too big advance can cause this issue due to too high compression before TDP.
Anyone faced this issue also?
Is there any other item I missed?

I will check ignitiion this evening.
I need to solve it quite urgent and have not much time to check a lot of things since I have a rally on Saturday.

Thanks a lot.