Getting massive stuttering here too. Seems to happen when the game autosaves.
I did rely on the Dark Sword for most of my first playthrough though, and spent a bit of time with the Irithyll Straight Sword as well.
I recently switched to a Luck/Faith build using Anri's Straight Sword. It does pretty beastly damage, especially buffed with Darkmoon Blade (Carthus Rouge is also nice). The only real downside is that it's pretty short compared to a lot of the other straight swords. Much prefer its moveset to the Dark Sword though. The specials and R2s are way better.Probably too late in the game to change now but whats everyone else using towards the end?
I did rely on the Dark Sword for most of my first playthrough though, and spent a bit of time with the Irithyll Straight Sword as well.