This is kind of funny.
Admin > Products > Catalog I set 2000 products per page (it now shows 999), however, the page never loads, apache2 is stuck with 100% CPU. The problem is that I cannot access this page any more.
One solution would be to change the value of products-per-page in database but I have no idea where this value could be. Another solution would be to delete the products from database and re-import them, but I'll keep that as last-hope solution.