if game is freezing for a second or short but noticeable period of time, in more or less equal time periods it's internal game process called "garbage collection" which tries to free temporary memory that is no longer used by the process, but to do so, it has to halt whole game. The more memory it has to free the longer it takes.
This mod is not causing that but because of it may increase framerate (sometimes 2 or 3x), every single mod that is using a lot of temporary memory per frame will now use it even more, simply because more frames will be rendered. I suggest doing a "divide and conquer" technique on your enabled mods to see which is causing excessive garbage memory generation (could be more than one). Disable half of them, check, disable next half or remaining if problem still occurs otherwise enable previous half but disable those you haven't disabled yet - It's really effective technique because you need only few tries instead of checking mods one by one - each consecutive try you will have 2x less mods remaining.

I had no idea such a process was going on in the background. TYSM for the info, I'll start hunting down that problematic mod.