Just to start this post off, you are allowed to keep gathering xp and rping without losing any speed on your real level. From what I understand, we level at the same pace with respective levels.
I suppose what happens is that the messages scale with the amount of xp the cap allows you to gather.
To better illustrate, imagine you do an action the gathers you 10xp. 10 is the average xp you are able to gather from that action.
If you continue gathering xp, the script will recognize the pace you are advancing in your level and lower the gain, to say, 8xp. If you are slowing down at gathering xp with your peers of the respective level you get an increase to xp. It will then go to 12xp if you are not playing as often. I believe there are extremes but they do not ever really cap I think. Not sure though.
Think of the scale like this.
2xp 4xp 6xp 8xp 10xp 12xp 14xp 16xp 18xp
| | |
Playing A Lot! Average Not Playing A Lot!
Each number comes with their own message, 10 being the standard. 2xp would be something like the "Proverbial wall" message and 18xp the "You are falling behind" or something like that message.
I don't have all the messages down but I believe that gives a relatively clear image. Anyways, what should be gathered here is that no matter the pace you advance in your level you will be about the same level as your peers given you play regularly. You will get your level when the math works itself out. So in essence, take a couple days off from the game if the mood hits you or do some hardcore grinding in a craft or RP.