Ah nevermind, I found this topic

https://kriesi.at/support/topic/how-to-prevent-anchor-links-to-jump-when-clicked/

Remove the smooth scrolling function in wp-content/themes/…/js/avia.js and delete following code helped me :D

//smooth scrooling
if(jQuery.fn.avia_smoothscroll)
jQuery(‘a[href*=#]’).avia_smoothscroll();

Sorry for bothering