How big is the Steam performance hit?

[NineNine]

I'm curious if anybody has tested to see how much of an impact Steam has on Factorio.

I know that I build big bases, so I need every last CPU cycle I can get. When I'm running my big bases, I'm not running extra programs in the background on my computer, because I'd really rather have the FPS/UPS in the game.

I don't have a Steam account, so I can't test it, but I'm wondering if anybody else has tested to see how big of an impact Steam has on FPS/UPS, as opposed to just running the game without all of the overhead. (I would assume that anybody who needs this kind of performance is already running Linux, too.)

[Tertius]

The CPU overhead of the ingame steam overlay, while it isn't showing? I would say zero. Nothing.

Additionally, modern CPUs have more CPU cores Factorio is able to use, so if the overlay wakes up to check if it has nothing to do, this would take place on some core that hasn't anything to do anyway. The same with 3rd party background apps: as long as such apps don't continuously add significant CPU usage, there is enough idle core performance for these apps.
I did screen-record Factorio gameplay with OBS, which is an expensive operation, but I didn't notice even one ups drop with some base that was already below 60 ups.

[SoShootMe]

The CPU overhead of the ingame steam overlay, while it isn't showing? I would say zero. Nothing.

Additionally, modern CPUs have more CPU cores Factorio is able to use, so if the overlay wakes up to check if it has nothing to do, this would take place on some core that hasn't anything to do anyway.

I agree most modern machines will leave some idle cores while playing Factorio (or one of many other games). Any impact from the Steam overlay is almost certainly unmeasurably small.

The same with 3rd party background apps: as long as such apps don't continuously add significant CPU usage, there is enough idle core performance for these apps.

Generally, the same as above applies, maybe even if the extra applications continuously use CPU. The memory they consume is more likely to indirectly cause a performance drop due to paging.

I did screen-record Factorio gameplay with OBS, which is an expensive operation, but I didn't notice even one ups drop with some base that was already below 60 ups.

This is much more likely to be hardware-dependent. For example, I'd expect a performance hit if you did this with onboard graphics, but that will never give you the best performance anyway.