Ehhh... not quite. There's evidence that copper runs closer to the speed of light (aka c), than fiber. Light through glass runs at around 2/3 c, making it the slowest option.

Wireless technically runs as fast as light, through atmosphere that's a tiny bit slower than c, but as close as we can get.

There's also a large argument among physisicts and electrician YouTubers about the speed of electricity through a wire, and I don't understand the conclusions, though they were articulated quite well by the YouTubers, it just didn't stick in my brain. The premise is how fast a lightbulb would illuminate if it had one light-second of pure copper (or superconducting) wire between the power source and the bulb, with little to no resistance. It's interesting but nuanced and complex.

Wifi, being EM waves (same as light) should run the fastest, copper ethernet close behind and fiber dragging it's heels at 2/3rds c. However, in practical applications, wifi has more to overcome since it's a shared medium. Copper and fiber have a dedicated medium, so they have no competition in signaling, wifi needs to contend with everything from other wifi networks spurious emissions from other frequencies, even background cosmic radiation, as well as itself (half duplex). Because of all of that, you generally end up with wifi in last because it has so many protections and checks that it delays itself to ensure that it's transmission will be recieved intact. The packets are generally larger and take longer to get started, so all the additional (mostly artificial) slowdowns make it slower. However, if you use highly directional antennas, a pair of them, on different but otherwise equivalent frequencies for send/receive, and cut out a lot of the other factors by designing the system well, then disable most of the protections because they're not needed by design, it will be faster, at least in terms of latency, than fiber or copper in almost every case.

Since designing a multi-access system that doesn't need wifi's protections is borderline impossible, this is limited to very controlled point to point systems where both ends are tightly constrained.

So the argument "wifi has a lower minimum latency" is correct, but irrelevant in 99.99% of use-cases. Copper is easier and cheaper than fiber and actually runs faster, than fiber, but it's only viable for extremely short runs, up to 100m in most cases, and fiber, while "slow" at 2/3rds c, is better for longer distance since there's less line-loss across the glass per foot.

This is a very deep topic and I'm no physicist, but I've been endlessly fascinated by this issue for a very long time. The information here is the result of my research over many years. I still consider fiber to be the gold standard of data communication, ethernet to be next-best and overall best for relatively short connections, and wireless to be dead last due to all the challenges it faces that are not easily overcome.

Unless you have no choice - a good WiFi will not add noticeable latency.

Myself I am playing over 5ghz wifi. I would say I don't feel much difference, but prefer cable any time!

Is the notebook or desktop wifi NIC and antenna important or only the router? Because when I had a shitty laptop a few years back the latency sucked ass, both at home and at my university (where I hope they had good network components but idk)

I just tested ping between my weak computers, one of which supports only 100mbit ethernet and are sequentially connected via cheap 2$ dumb switch and ISP-provided router and got 0.187ms average, while ping via same system, but using 802.11ac for one device got 8.16ms with standard deviation of 11.9, maximum of 67ms and minimum of 1.44ms.

Right. Like even in the shittiest scenario that's not a major difference. There's stuff like interference and the speeds are lower, sure, but 1 gigabit is plenty for non enterprise situations

Maybe....

your latency on your network might be 0.6ms, but for most practical use-cases, it will be orders of magnitude more. Partly due to the interference and half duplex nature of wifi, but also because of CSMA/CA (carrier sense multi access / collision avoidance) algorithm, which listens before transmitting to ensure the channel is clear, and waits when it's busy until it's clear before transmitting. The actual transit time for each frame is very short, but getting to the point where you can actually transmit is the main challenge for wifi.

Propegation time for a 1500 byte frame on gigabit Ethernet is approximately 12 µs, or 12 microseconds, aka 0.012 ms. So the argument is kind of squished here. Given that you have a dedicated channel to the switch (and not needing a carrier sense, collision avoidance of detection algorithm with ethernet) the frame can be immediately sent, so the total transit time from a computer connected by ethernet to a router or switch is orders of magnitude faster.

I meant to say 5ghz

not many games use UDP for their transport

Citation Needed

I have never heard of a latency-sensitive game that doesn’t use UDP for inner loop communication. Sure they use TCP for login and server browser, but the actual communication for gameplay almost always uses UDP.