Generate picuture thumbnail using Multithread?

Currently it is slow when showing a directory in which there are many large size photos by DSLR. Can we generate thumbnails using multithread? I have a 18-core processer but it has no use.

It already does that. You can set the number of threads in Preferences.

Oh, thank you. Could we make it auto to decide the number of thread according to the processor? And can there be an option to use internal thumbnail in EXIF?

What kind of files are we talking about? JPEG, or raw, or something else?

What dimensions?