pfSense

The default settings for ARC in FreeBSD are appropriate to optimise disk access for most computer systems.
For a real time system such as pfsense which is not typically disk speed limited, the default settings and progressive wired memory use by ARC is not optimal for most pfsense installations.
As zfs is now the default file system for pfsense, expecting most users to debug their high memory use and explicitly code a solution is less than ideal.

Adding a GUI interface to at least vfs.zfs.arc.max and setting it to a default appropriate for pfsense would be a valuable enhancement.
This could be done by

• Adding an entry in System -> Advanced -> System Tunables
• Adding a section near "Ram Disk" in System -> Advanced -> Miscellaneous