Lightroom Classic: Autoimport + Smart-Previews??

You're right, that option's not there. You can create smart previews on demand by selecting them and going to Library menu > Previews > Build Smart Previews. That way it can run later when the computer's not so busy.

Thanks a lot for your fast reply!! Yes - usually that would work fine. But in my case I need a solution that doesn't need my prompting/confirmation. I want to put my sd-card in the slot of my macbook-pro while I'm shooting and the computer shall do the rest of the work (importing and creating of the smart-previews) so that I can start editing immediately after the shoot. I already have a script that's copying the pictures to my laptops harddrive :-( but lightrooms autoimport is not allowing to create smartpreviews and the "folder watch"-plugin is creating additional 1:1 previews which slows the whole process so that when I want to start working only 20% or so of the importing process is finished.
it really is a big challenge just to be able to start working after a shoot without waiting for hours till the catalog is ready. It will be a pain in the ass but I guess i will have to switch to capture one or another alternative because of this little problem! hmpf ...

I'll switch this to a feature request because I don't remember anyone requesting it before. 

Silly question, but for what purpose are you creating the smart previews, that is delaying you from editing the photos immediately after the shoot?