Postgres 9.6: Inserts Very Slow After Reboot

I'm experiencing a strange issue when importing data into postgres. I have an import script that runs once daily at night via cronjob on a Linux OS (Linux 4.9.0-5-amd64 #1 SMP Debi

Solution 1:

This happened to me once. Don't really know why, but for me it was fixed after restarting the postgresql service. My thinking says that if you do not restart the service(even after a reboot), it seems postgres keeps its WAL (Write-Ahead Logging). By restarting the service everything cleans up, so everything runs as good as new again. But, perhaps there's another reason. Anyway, try restarting the service instead of rebooting or restart the service after reboot.

Read the question comments for more info or this link that @user35934 posted.