[stock_toaster]

You might also try setting primarycache=metadata, to avoid double caching the data. From what I have been told, this can help reduce memory pressure of the ARC competing with postgres' own caching.

Are you also setting a max limit for the ARC? You don't want postgres and the zfs ARC to compete for memory. I wonder if this impacts FreeBSD's poor performance in the read intensive tests.

[kovacik]

I actually did try this and the results were worse. I did not investigate it further and went with primarycache=all