Two things : the more influence you have above resting point with a CS, the more influence you lose every turn.
And, influence per turn scales with game speed. The slower, the less influence you get per turn.
Also, VS personality changes initial influence lost per turn.
So, it might be a combination of both.
Check for another CS with similar above-resting point influence (and personality), and check if it match. At Epic speed, you should expect ~3.33 more influence. At marathon, it should be ~1.67.