On April 25 of last year, I had a post titled essentially the same thing.
I did Spinervals DVD 23.0 - Time Saver 1, workout B: Tempo/TT. I about died.
Because of that experience, I'd been putting off doing that exact workout again, even though I've done workout A (technique) a whole bunch and have done C (sprint/power) once or twice as well.
However, since I didn't have a lot of time to ride today and I needed to get in a tougher workout, I decided to chance B:Tempo/TT again.
And ... it was surprisingly easy. Granted, my legs still hated me through good chunks of it, but I didn't have nearly the lung/cardiovascular problems as I did last year.
Just proving once again that visible progress is the best progress to have.