Does it make sense to make to make (at least) session table to UNLOGGED? I don't think we're losing much here (losing table contents after crash - which could be in fact better for client recoveries) and gaining some speed on this overused table.
I wouldn't rush into this. Suddenly forgetting every session forces all clients to re-authenticate. This situation gives them an AuthError rather than AuthExpired, and I'm not sure how that will play out for all clients.
AuthError
AuthExpired
That said, it's certainly a tempting change, and the data is not long lived.
Metadata Update from @mikem: - Custom field Size adjusted to None
This issue has been migrated to Fedora Forge: https://forge.fedoraproject.org/koji/koji/issues/3625
Please continue any further discussion there.