Category element shows vertical first in stead of horizontal directly

Our category element is flipping on load. How to fix this? we dont want to be it to get loaded that way. It interupts our page speed score, which is really low with this theme also.

Added two screenshots, when loading it get loaded vertical first, then horizotal. Very irritating when visiting the website. I even get an error with uploading files to the attachment. Please check the website for the problem. It is the element on the homepage with oorbellen, kettingen, ringen etc.