Theme focus on mobiles and tablets

I looking for at theme focus on mobiles and tablets. Those are the most popular devices among my users. Desktop is not a priority.
I guess a fast load theme like NickCates’ Forward… but I would appreciate any advice.
By the way, how much slower are stack pages vs markdown or html pages? Does it makes a big different in load speed terms?
Currently working on RW6

I am pretty new weaver myself but your question was interesting.

While most of the new themes are responsive and have an option to hide content from the mobile device, content is still loaded at the back ground and hence affects loading time. Joe Workman has a stack called Agent that allows a user to specify shown the content same way with a difference that hidden content is not loaded in the background. Is the difference tangible in practice I cannot say for even I have the stack haven’t got around to use it yet, I guess it comes to the size of content…

I know that’s pretty generic advice, but hope it helps.

Thx Tapio.
Maybe a workaround is to have two versions of the website. The mobile version -I am concern about- and a second one build for Desktop. So depending on the device it is auto loaded one or another (kind of language versions). Does it make any sense?