Suppose you have the choice between leading a lane or being at the back of a slightly faster lane, which would you prefer?
I definitely swim better (and faster) at the back of the faster lane but perhaps it's all draft, so leading the slower one gives a better idea of where I really am?
Lead the lane, feel the fear and shame of being passed, get motivated, swim faster
...unless everybody behind you likes to push off without waiting the requisite 5-10 seconds. In that case, you push off right on their feet and ride them like a donkey:D.
If you ain't the lead dog, the scenery never changes.
This... leading the next lane up would be the goal. That isn't going to happen if you stay in your current lane. I don't love leading but man I hate other people's feet and I hate people on my own feet... sometimes that is the one thing motivating me at 5 am!