Err.. u've fixed the swimming bug.... partially.
I've encountered a mission cave entrance which required swimming to enter. Nice.
But after zoning in.. I've ended up moving at my SWIM SPEED. Which is damm slow for most pple :D
The work around fix: Go into SNEAK mode (H) and Un-Sneak. It will reset your run speed.
Minor bug with a ready work around. Just posting here so that u could fix it at your own leisure :p