List of Leads too Slow

I am experiencing a low performance from SuiteCRM when loading list of leads.
My entries are over 400k, but it looks like even if I have a paging of 50 records, it looks like it’s loading the whole amount of entries before showing 50 of them. Do you know a way to increase perfomance or to solve this problem.
Thanks a lot in advance

I believe there is some information for this somewhere but in general this should help you: