If the problem is that your coworker is slow, your whole team will do better if you help them get faster. Of course, they need to want assistance, so the way you offer it makes all the difference in the world. Next time they are working on a bug, just casually ask if you can help them look at anything. If they accept the help, give gentle advice and pointers on how to speed up the investigation.
If your coworker realizes that you are really helpful, then soon they will start coming to you for assistance. That's great, because eventually people will see them at your desk getting consultation and helping them work through problems. If several coworkers are seen coming your desk regularly for help, then others will eventually realize that you are a thought leader and problem solver, and your coworkers will eventually start saying things like: "Well, this would go a lot faster if we had Green Baloon here. Ted, can you go see if he's at his desk?"
The goal is not for your boss to see that you work 5x faster than the rest of your team. The goal is for your boss to say: "Huh...it used to take 3-4 days for you guys to turn around these bugs, but now you're destroying them in a few hours. What's the difference?" At this point, the responses will depend very much on how your coworkers view you. If they think you are arrogant or will try to steal all the credit, they will just take credit themselves and say that they've been leveling up their skills, while you appear to be sitting still. If, on the other hand, they see you as someone who is generous with his time and willing to do what it takes to move the whole team forward, then they will be happy to give you credit for helping them out. They might do it indirectly, like: "Well, Green Baloon shared some scripts with the team that have really helped us power through some issues", but if you have done a very good job of being a team player, they should feel comfortable saying something like: "Green Baloon is the go-to guy when we get stuck, truth be told."
You have to use your own personal judgment to decide what kind of coworkers you have, and what kind of responses they are likely to give in the scenario above when you decide to invest in them as team members. If they are a bit selfish, then you should probably do the minimum to keep the team unblocked and working on the good stuff. If they are fair-minded, then investing extra time in skilling them up will eventually turn into positive press for you one way or another. The key is to make it clear that you are trying to help them and help the team, and not just taking credit for fixing stuff.
When it comes time for reviews, you want to have a history of good work that you've done. So when you contribute tools to the team, write it down in your personal journal. When you help other people, write it down. When your boss asks why you think you deserve a raise/promotion, bring out your journal. Don't focus on who you have helped, but rather, how you have become a force multiplier that makes the whole team faster and more efficient, which also helps your boss look better. It's not about: "I'm 5x faster than Ted." It's about: "Well, you may have noticed that the team is getting stuff done faster. Let me show you some of the reasons why."
Once your boss figures out that you are improving the whole team, if they have two brain cells to rub together, they will realize that you are their meal ticket to advancement. If they are a bit slow on the uptake, spell out this obvious fact for them, as diplomatically as possible: "So, what do the other directors say about our department? How have you been selling our work? Did your boss notice our throughput has gone up? Surely that's been good for you, hasn't it?" Make it clear that your boss gets to take credit for your whole team improving. They will figure out that it didn't happen magically, and if they want more improvement, they have to reward the person who is actually driving the changes.
If your team and/or boss don't respond positively to your best efforts, then it's time to switch teams/company.