Ubuntu not working properly after install dual boot

I downloaded ubuntu 18.04 LTS and installed it “alongside windows 10”. The installation works fine. I remove the installation media, restart and choose Ubuntu in GRUB.

Once I get in to ubuntu my resolution is 1024 x 576 or something windows popping up are not visible at first. I have to drag my mouse over windows to reveal parts of them. I can’t change resolution in display settings etc. On top of this it is really slow.

What could be the problem?