I was playing a round with 1000x slots. I found a loophole where, once you put in enough prod mods, the speed hits some minimum threshold (perhaps 0.2), and then every subsequent prod mod just increased output per second.

Is there any existing mod or ability to mod this kind of minimum threshold?

To my knowledge, this is a hard limit within the game engine.

There's another limit, when a recipe craft reaches near or below 1/tick. Crafting speed is limited to 1/tick. Productivity is based on how much /would/ be crafted... as in more than 1/tick produces excessive amounts.

Both are limits of the game engine. Haven't heard any changes for 2.0 about it, there may be none (though quality 5 stuff with barrels and modules might break... who knows)

Cool thanks, yeah I also went through the Mod API and didn't see anything. Let's see what 2.0 might bring. :)