Rate of position updates from gmapping

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Hey folks,

I am using a 2D SLAM with Navigation stack and Gmapping. My odometry is not so accurate and once I start to move I slightly drift from the real position. The localization algorithm on gmapping compensates my error but the problem is that is a bit slow for my application. I receive a correction almost every 5 secs and I want to make it faster like amcl which does the same thing almost in real time (The problem with amcl is that it only works if you have a map and I want to do slam). I went through the parameters available on gmapping and couldn't find any thing related to the rate of updates that I am receiving from localization.

Any ideas? Thank you very much in advance