I can confirm what has been said, there are a lot of levels I find simply too boring to spend time speedrunning them. All in all I haven't speedrun that many levels, although what I have speedrun I tried to optimize to my best.
I also have speedrun levels mostly with Meat Boy and rarely using the fastest character.
I nearly don't play the game at all anymore anyway, although I might get back to it from time to time. Besides, 73L and Takuji and even Raginzfranz are too active for me to have much chance of beating their new times (at least, not without much effort, which I'm lazy to provide
. Too many games to play, too little time, etc.).