I did the thing EA_David suggested, with the cleaner and the origin purging and after the game finished downloading again, the performance is even worse.
The game on release: about 50 fps, some stuttering (settings on high/ultra)
After patches: I'd say about 15, with major stuttering, sometimes freezes up to 20 seconds. (graphics on low, medium, high doesn't make any difference at all)
After CCleaner and all that: Major stuttering and lag in the game's main menu, game frozen 90% of the time, with short 5-10 second bursts of functionality.
The only thing that has done any good for me after the patch (and that only worked once, temporarily, for about 90 minutes until the game crashed, and it hasn't worked since) was to put all the graphic settings on max (decided to try that on a whim, since it worked on Age of Conan when that was released). The game worked almost as good as pre patch for those 90 minutes.
I get that this is complicated stuff to work out a solution for, but why then force the patch on those of us for whom the game was working great?