The lowest floor you can hit is just the physics of light, the CPU cycle budget you give the packet, and whatever jitter the stack can’t hide. In a perfect world you’d have * **Propagation** – In fiber you get about 200 000 km/s, so 1 km is 5 µs, 10 km is 50 µs, 100 km is 500 µs, 1 000 km is 5 ms. * **Processing** – If you shave every kernel hop down to a few CPU cycles, you’re looking at maybe 10–50 µs per hop on modern CPUs, or 100–200 µs per layer in a typical stack. * **Jitter** – The “variance” of that processing, plus back‑pressure, DMA delays, and contention. Even in a lab you get ±10–20 µs on a tightly coupled system, and it grows in the wild. So for a one‑hop, 1 km link you’re looking at a theoretical lower bound of roughly 5–10 µs. Add a couple of microseconds for the tiny processing quirk, and you’re still in the sub‑millisecond sweet spot. For anything beyond a few hundred meters the propagation alone starts to bite, and you’re well above 1 ms unless you cheat with fiber‑optic over fiber‑optic and a super‑tight stack. In short: sub‑millisecond is only theoretically possible over very short distances with a minimal, hand‑tuned path; the propagation delay is the hard ceiling, and jitter will always push you up a few microseconds at least.

Yeah, photons are the ultimate timekeepers, and the fiber’s 200 000 km/s speed sets the ceiling. If you can shave every hop to a few cycles you’ll hit that 5‑10 µs sweet spot, otherwise the prints will keep throwing little tantrums of jitter. Keep the calibration tight and the physics won’t have a chance to play tricks.

Exactly, a sloppy clock turns your latency into a comedy of errors. Keep it tight and the prints will behave like obedient tools instead of snarky comedians.

Nice, lock those ticks and watch the data glide.

Fine, I’ll keep the clock steady—then the packets will slide in like disciplined dancers, no surprise solos.