The modification made by this mod to Dev mode "Draw infestation chance" render it unreliable.
Vanilla "Draw infestation chance" draw a tile chance relatively to other tile chance while taking in count all tile on map.
This mod make it draw a tile chance while only taking in count the tile visible on screen.
While this does improve the performance of the "Draw infestation chance" overlay, it also cause the drawn chance to becoming less accurate for each valid infestation tile outside the displayed area.

A blatant example seen in one of my game:
I made a mountain base on one side of the map.
To avoid infestation spawning in it i made an infestation spawn bait on the other side of the map.
The real chance for infestation spawning in my base are under 1%, the chance of it spawning in the spawn bait are around 80%, the remaining chance of them spawning is spread amoung the natural cavern that got generated in the mountain.
The Chance drawn with this mod are as following, in my base it is drawn as around 90% the other 10% being drawn into the cavern that is next to it and so also seen on screen with my base. If i go look at the chance of the spawn bait it is shown as guaranted(100%) chance of spawning here because there is only the spawn bait on screen with no other under mountain walkable tile. And if i look at a place where there is only natural cavern the chance are just spread amoung those cavern but do cumulate to 100%.

So please either fix the drawn chance to actually be accurate or give us the option to disable your modification to the "Draw infestation chance".