I think this is a sit-down-and-think moment.
What do you want? What would be nice, but you're willing to live without? What things are so terrible that even keeping this friendship isn't worth it?
When I was in high school, I met a girl freshman year who was smart, creative, and a straight-A student -- everything I wanted to be, dreamed that I was, but was afraid that I wasn't. We have similar build and hair color, so people often asked if we were sisters. By senior year we were so close that we answered, "yes."
I found myself getting frustrated with her a few months ago. She was so.. set in her ways, so small. In a moment of shock, I realised that she hadn't gotten smaller. I'd grown.
So I found myself in the same boat. Things that I never noticed before -- or things that I'd enjoyed or admired -- now irritated me. I sat clenching my teeth rather than pointing out her stupidity. And yet, losing this friendship would be as bad as losing a blood-related sibling.
So I sat down and did some soul-searching, and determined my limits. I want to be her friend. I want to help her as much as possible. But I want to continue my growth -- and I will sacrifice the other two if (and only if) that's the only way to continue growing.
It turns out it's not. Our disagreements are mostly in politics (She thinks Bush is always right, I think it's our patriotic duty to make fun of anyone in office) and socializing (she thinks that people are lazy, stupid, greedy and manipulative. I choose not to live in that world). So we don't talk about it. I still disagree with her if the subject comes up, but I choose not to argue it -- the friendship is more important. And I make sure that no matter what, I still show that I love her.
So what are your limits? Do you want to work with him on projects, or do you want to get them in on time? Do you want to ride with him to school/work, or do you want to arrive when you choose? Either answer is OK, but you have to deliberatly choose. And if you say, "I like to have plenty of time to finish a project, but it's worth it to me to grind my teeth over tardiness in order to work with him" then you don't get to complain about it anymore.
If you decide that getting places on time is more important, than tell him that, and give him the option. Say, "I really enjoy the extra time I get to spend with you when we ride together, but it's a problem for me that we can't get going as soon as I get here. I don't want to interfere with your schedule, so I wanted to let you know and give you a choice. Do you think that when we schedule to go some place, we can pick a time that you'll definitly be ready by? Or would that be a huge problem and you'd rather just meet there?"
That's the practical side. The emotional side is harder, because it's likely that neither of you really has a fully clear picture of what he's feeling. I'm going to make a guess, based on what I'd be feeling, but I can't say for your friend.
- He's jealous Be honest. Wouldn't you be? It's perfectly natural, even among friends. Even when you think it's GREAT that your friend did so well, and you're thrilled, and you'd support him all the way -- there's still that little voice back there saying, "Why not me?"
- He's frustrated It's entirely possible that he sees you doing well, and wants to do that well also. Procrastination is a hard habit to break, even if you do know how to go about it. He's trying to get better, trying to be the kind of person you'd want to spend time with again, but he can't seem to manage it.
- He's hurt He's jealous of you, and he's frustrated that he can't do that well, and your response is to get mad at him. Granted that you have good reasons, but that's got to hurt him.
- He's scared There's all kinds of things in this situation to bring up fear. He's afraid that he's losing your friendship. He's afraid that he's losing a good partner for projects. He's afraid that he'll never be able to be that good. He's afraid that you don't like him anymore. He's afraid that you SHOULDN'T like him anymore. And the fear causes him to retreat to tried-and-true paths -- like procrastination.
What to do about all that is for you to decide. But if you really do want to keep this friendship, and you're not just hanging on to it for convenience and old times' sake, then you have to let him know that. Say, "I know I've probably been short with you sometimes lately, and I'm sorry if that hurts you. It's very frustrating to me when (late/won't get started/doesn't meet commitment). That's why I wanted to talk to you about it. I want to find a way that we can meet both of our needs on this, and still be friends. Maybe that means we shouldn't work together on projects, or maybe we just need to revisit what jobs each of us is doing. What do you think?" Emphasize that you want very much to be friends with him, and you're willing to negotiate or discuss priorities, or help him in whatever way necessary to stay friends. And if he says, "Actually, I was wondering if you could help me stop procrastinating.." then you've kept a friend, gotten a better partner, and helped someone out, all in one conversation!