about ~4ups impact

It really depends on multiple factors:

• Frequency to save the screenshots. Taking the screenshot takes time, so in between there is no (barely) impact
• Resolution of the screenshots (more pixels is more time)
• Used trackers, albeit low when you build, walk, launch rockets, etc. the camera positions need to be recalculated
• Smooth zooming, same as previous: camera position need calculations
• 'left over' CPU resources. If your CPU is struggling to keep your factory running, there is an higher (more noticeable) impact

And probably more...

So without much context, we cannot say much.
If there is something you want to ask or try out in order to reduce UPS, let me know and we can see if there are ways to improve.

Thank you for the detailed reply.
I haven't tested any settings other than the default ones. I've noticed that I encounter some stuttering (UPS, sometimes drops to the 40-50 range) with the same factory that normally achieves a consistent 60 UPS. This issue seems to be resolved when I pause the recording or remove the mod.
From your perspective, what are the most important settings I can adjust to improve my UPS without significantly compromising the quality of the timelapse?
Tyvm for your help.

The mod uses Factorio (API) to make screenshots, so there not much that can be done here without reducing the resolution.

Only thing is that by default the mod takes quite a bunch of screenshots (the timelapse is pretty slow). By increasing the speed gain, the timelapse will be faster (more time between each frame/screenshot), so there are less slow downs. But on each screenshot the slowdown will be there...

On long runs like pyanodon mods, it makes sense to only have 1 screenshot per 5 to 10 minutes, to prevent having a daylong timelapse in the end... So the slowdowns are really once in a while (5 to 10 minutes actually)

Note that removing other (unused) mods could free up your 'left over resources', giving more resources to the mod and having less severe slow downs. But this only works if you are not using those other mods (albeit them being loaded).

Buying a better PC of course also helps... :'(

All in all: not much you can do without compromising the quality I am afraid