My FPS drops into 40.0 when no-one is on the track. But when 1 or more drivers are on track, my fps is normal (62.5 because of lock). It has appeared since 0.6E or older, I don't remember so good.

Quote from racer autov8 :

It has appeared since 0.6E or older, I don't remember so good.

Or it has been like that for always.... When nobody is on track the game limits itself to 40 fps to save power.

I noticed the 40fps thingy too a while ago, but never tought its how LFS is meant to work. I was thinking my laptop is going funny

I'd consider that a bug still, because when you do SHIFT+U it doesn't make sense anymore as you move camera.