I would have said, check your shared buffers memory and concurrency are configured right for the environment you are running on. The defaults are wrong for most production environments and the right values are highly server dependent. If you haven't specifically tuned them for your production server, chances are they are wrong and you are leaving substantial memory and / or concurrency on the table.
I don't have links right now, but if you search for something like "online postgres config tool", you should find two different pages that do the same thing - you enter some data about your environment, and it spits out recommended settings.
