Why is it that ebay-kleinangebote.de has barely been usable on a laptop with Firefox for weeks?

At the same time, there are a lot of ads from other people in it, so it works for them after all. Can it be that it only works properly on smartphones? Or do you have to do something special so that it loads better and not constantly hindered by websites in the background?

Works great for me with Firefox and on the laptop, was online there myself. Delete your cookies and see if you really have the latest version of Firefox. And check your laptop for updates. That can bring a lot.