From the video you made:

a) when you fetch 4791 records there are more then 1M record reads at 3 tables (HD_STATUS, etc)  (0:58 at video)

b) when you fetch 4790 records there are just 21K record reads at same 3 tables (HD_STATUS, etc) (1:32 at video)

I.e. there is a lot of records in one of that 3 tables which have no corresponding records at other tables to join.

No wonder it need more time to read >1M records than 21K records

Regards,

Vlad