Hi Felix,
Another possibility would be to decrease the road speed at the turn/intersection by 1 or 2 levels - then have the turn/intersection. At road-speed 0 or 1 it is already much better - and the overall time for the way will decrease! (if you have 10meters in and out of the turn with lower road-speed).
I'm afraid this could greatly increase time for calculating a route. I have done tests with some commercial data and cGPSmapper. I'm not sure if results are directly compatible with mkgmap, but in my opinion, for routing speed most important is the number of roads (class 4 roads in case of long distance routes). Single road with multiple nodes (junctions) is better than the same nodes arranged as multiple roads. -- Best regards, Andrzej