The general concensus was yes, they increase stuttering, as the game has to wait for the different threads to finish before it can continue. There was a large thread regards it a couple years ago which concluded that, as Oblivion isn't properly configured for dual core, it can't do it properly!
Interesting, thank you for this. As someone recently returned to Oblivion I had missed this and just did the same changes to the ini that I did to Fallout games, assuming it would be helpful. So all the edits with the word thread in them should actually be set to 0 for better performance? What about the other changes listed on tweakguides such as bbackgroundload and so on?