Is this an insert only table and perhaps not being picked up by autovacuum? If so, try a manual "vacuum analyze" before/after each batch run perhaps. You don't mention updates, but also have been adjusting fillfactor so I am not not sure.
- Sudden insert performance degradation Henrique Montenegro
- Re: Sudden insert performance degradation Sebastian Dressler
- Re: Sudden insert performance degradation Henrique Montenegro
- Re: Sudden insert performance degradation Sebastian Dressler
- Re: Sudden insert performance degrada... Henrique Montenegro
- Re: Sudden insert performance degradation Michael Lewis
- Re: Sudden insert performance degradation Henrique Montenegro
- Re: Sudden insert performance degradation Jeff Janes
- Re: Sudden insert performance degradation Henrique Montenegro
- Re: Sudden insert performance degradation Henrique Montenegro
- Re: Sudden insert performance degrada... Sebastian Dressler
- Re: Sudden insert performance de... Henrique Montenegro
- Re: Sudden insert performanc... Henrique Montenegro
- Re: Sudden insert perfor... Justin Pryzby