in order to limit the memory usage of my page, I need to limit the entries number on the page sites.php (for network management)

I tried to a filter with $pagenow == sites.php but that didnt work. I found a filter to restrict the sortable columns ('manage_sites-network_sortable_columns') but nothing to limit the number or item per page.

Do you have any ideas how to resolve that?

Thanks in advance.