Sub always going slow on the strategic map

[CmdrCollins]

[...] it appears that the diesel subs always run a little slower than the regular subs.

Campaign map speed is directly related to the maximum submerged speed of your vessel (as defined in /vessels/<vesselname>.txt; SubmergedSpeed).

For quite some time my Sub is always going slow on the strategic map [...]

When loading a save, the game will load the value for SubmergedSpeed from the first ship in /vessels/_vessel_list.txt, rather than from the ship you are currently playing. For the Russian subs mod, this happens to be the Guppy IIa, one of the slowest subs available (17.5kn).

This bug is much less noticable in vanilla as the Los Angeles (fastest playable) occupies the top spot.

Any idea how to solve that?

Go to /override/vessels/_vessel_list.txt, find the line mentioning the sub you are playing, and move that line to the top of the file (eg usn_ssn_seawolf for the Seawolf).