Other things that it could be: throwout bearing/clutch disengagement fork causing the plate to engagage irregularly… remember to thoroughly clean and lubricate the ball pivot and the thowout bearing guide. Also, inspect for wear on the fork. On my old maxima, the clutch slave used to stick occaisionally too. Check that for free movement as well.
one other thing… this would be a stretch… The car feels slower? Ok. It could be that the ebrake is sticking. This would cause jerky starts and make the engagement of the clutch harsher. It would also go away as the rear pads heated up and began to liquefy. Brakes smell alot like clutch… just an out there idea to look into before you pull the transmission…