What constitutes major you say?
If a game fails to hold 60 fps more than 60% of the time, it is SEVERE...and TTS is quite severe. Throughout normal play, the framerate will bounce between 30 and 60 fps very often. I've gone over this in GREAT detail previously, so I don't particularly feel like typing a lot on this...but I will if I have to.
Basically, with TTS, almost all combat situations will run at 30 fps. What's worse, is that the game often flucuates between 30 and 60 on a regular basis. Combat is typically 30 fps and exploration is usually 60 fps...but there are plenty of times where walking down a hallway will trigger bouts of slowdown. It makes the game look VERY jumpy. If you stop in any room and pan the camera in a circle, there is a damn good chance that it will jump between 30 and 60 fps as you rotate. This slowdown is NOT something rare nor do you have to be nitpicky to see it. It occurs throughout the game in virtually every area. There are exceptions to this, of course, but by and large, the game just can't hold a steady framerate. The dips are as frequent as the Japanese version of Sega Rally 2 for DC. It bothers me so much because it is like a painful tease. You get these pockets of 60 fps, but it always feels as if the game is about to chop up...and it often does.