That 5.5mb update you may or may not have seen being applied to Dark Souls through Steam was the removal of multiplayer region locking. Players have been asking for this since the game’s move to Steamworks from Games for Windows Live, as being limited to co-op and PvP choices in one region is rather restrictive.
The patch isn’t (at the time of writing) accompanied by any notes, but there’s enough unofficial confirmation of the region lock removal out there for me to be pretty confident that this is what’s been changed.
Especially as Bandai Namco’s J. Kartje confirmed an upcoming Dark Souls region lock fix a few days ago:
And if you're wondering about region-locking re: DS1 – I've heard a fix is done and it's being tested. I hope for deployment soon.
— J. Kartje (@JKartje) January 14, 2015
The latest update has broken the FPS unlocking aspect of DSFix 2.3, so you’ll need to download and set-up Durante’s newly released DSFix 2.4 if you want to get back to playing at 60fps.
Happily, he mentions in the release blog notes that FPS-unlock creator Nwks has implemented a solution which should prevent future updates from breaking DSFix.
“The only reason this would fail is if the binary code right around the places which need to be patched were to change, which seems unlikely for the smaller patches which can be expected at this point.”
In light of that, DSFix 2.4 may be the final edition of the port-redeeming program.