My website is too slow

Dear all,
On my devices (phone, iPad, laptop) it takes appr. 6 seconds to fully load my website. Also the dashboard (where I can make new posts, edit posts etc.) is quite slow.
I’ve tried to narrow down the problem, but have not been able to pinpoint where the problem is:
– Deactivated all plugins (only Jetpack has a minimal effect on the speed)
– Tried several themes
– Changed pictures (used lower resolution)

Can you please check if you also think it is too slow? Ideally, it should open within 1-2 seconds.

Is it an option to create the site from scratch? (do a fresh install)

Thanks.

The page I need help with: [log in to see the link]