City of Heroes developer Matt "Positron" Miller answered some questions about XP Curve Smoothing in a developer Q&A:
XP Curve Smoothing
Q&A with Matt "Positron" Miller
Q: Please tell us what exactly this XP Curve "Smoothing" means.
A: Well, the leveling speed "curve" looked like a jagged mountain slope more than a smooth line. There were some levels in City of Heroes and City of Villains that just took players longer to get through. This was due to a variety of reasons, mostly in the realm of available mission content. We have tried to add new content in those areas over the past few updates, but a stronger hand was needed in some of the real problem areas. We went in and, through data mining, determined how long characters "lived" (existed) at any given level. This pointed out exactly where our problem areas were and exactly how we could address them. In addition we did a near global increase to the XP earned for defeating enemies. This will have everyone leveling faster than previous issues.
Q: What made you decide to implement this?
A: Our players had legitimate complaints that certain levels acted like brick walls in developing their characters. We wanted to eliminate those walls wherever possible, and in the process speed up leveling for everyone.
Q: Does it fundamentally change anything about the game?
A: Definitely, players will see more progress on their XP bars in the same amount of play time they are used to. In addition, levels where they felt "stuck" should go by MUCH more quickly now.
Q: Are you concerned that this will allow players to level up too quickly now?
A: That's always a concern, but we are always looking to add things for max-level characters to do to improve themselves. In addition, the Ouroboros (flashback) system allows players to go back and play content they may have missed, so even if they have outleveled a story arc or a badge-given mission they can go back and get it.
Q: When will this go live?
A: We expect this to be live before Valentine's Day.
Q: Is there anything else that you want to say about this?
A: I am really excited about being able to bring this improvement to the players. This is nothing but a hugely positive step for the 'City Of' games.