I noticed something after updating from 0.2 to 0.4
When I first loaded a previous save I had a belt in hand already, then pressed 'q' to put back in inv and a message popped up "47"

I removed a belt from a row and again, "47"

I removed some other mods I had updated today first, but still "47" upon load and "47" when I removed the belt.

I removed this mod and installed the previous version 0.2 and the messages stopped.

I'm guessing when you changed update speed it did something to post update message about the amount of extra spaces? or something? Idk i'm not a modder so i'm "out of my element" as it were.

Furthermore it would occasionaly post "47" on its own. There almost seemed to be a pattern but I didn't really try and catch it

I have a feeling it's the number of items using it or w/e

Disabled it and didn't get any messages in a new game.

Edit: Found it
Extract the mod and edit the control.lua to remove the "player.print(newBonus)" line in the changeInventorySlots function

Whoops, I added a line so that I could see the mod was doing stuff, forgot to take it out. (Btw, these topics do not notify the mod owner, so it's better off to shoot me an email than to post here.)