SideMiniSidecar basics
Wired or wireless Sidecar: latency, battery and when each one wins
Sidecar runs over a USB cable or over Wi‑Fi, and Apple presents them as equals. In daily use they are not. The cable is steadier and charges the iPad; wireless is tidier and good enough for text. Here is the honest difference and the one failure mode nobody warns you about.
Responsiveness
Over a cable, pointer movement and scrolling feel close to a real monitor. Over Wi‑Fi they usually do too, right up until the network gets busy, and then the picture goes soft during motion and recovers a moment later. Video and animation show it first; text and code rarely do.
Neither path is good enough for gaming or colour work, and that is a property of Sidecar rather than the transport.
Battery and heat
Wireless Sidecar is a real draw on the iPad: the screen is on continuously and the radio is busy. A full working day is not realistic on an older iPad without charging.
The cable removes the problem entirely because the Mac charges the iPad while it works. For a Mac mini that uses the iPad as its only screen, this is the deciding argument: an iPad that goes flat overnight takes the Mac’s only display with it.
Reliability
Wireless depends on both devices staying close, on Bluetooth for discovery, and on nothing else saturating the band. Personal Hotspot or Internet Sharing on either device blocks Sidecar completely.
The cable removes those variables, but adds one of its own: it has to be a data cable and the iPad must have trusted the Mac. A charge-only cable looks identical and does nothing.
The wired path that fails while wireless works
On some Macs, asking Sidecar for the wired transport specifically fails with a device-not-found error while the plain connection succeeds immediately. macOS shows its own alert for each attempt, which is how you notice.
It is not your cable. If you see it, connect the ordinary way and the cable still charges the iPad. SideMini detects the failure once and then stops requesting the wired path, so the alert appears at most a single time.
How to choose
iPad on the desk, all day: cable. iPad in your hands on the sofa: wireless. iPad as the only screen of a Mac mini: cable, without hesitation. Travelling with a MacBook: whichever cable you already carry, and wireless when you have run out of ports.