I have now built up a pretty simple website, with a few images.
It works properly on pc and mac, but struggles on my iPhone.
I have used Squash for compressing my images.
I suspect maybe the front page is the problem.
I could get your site to work on occasion on mobile, I needed to reload once or twice. You have a pretty massive image on your page (3.4MB; 4912px x 3264px). Maybe your site it stalling out from the large image?
As for contact form, not sure, we’d probably need a few more details. What are your form settings and where is the email coming from? If it is not being sent from an address the same as your domain (i.e. info at kristianroald dot com or something similar) that could be the problem.