I use their current (now prior, I guess) chip reader, and it completes the transaction within just a second or two. Most of my customers are surprised it's so fast, compared to other chip reading registers around town.

That could be because I'm using a cellular internet conneciton however. My town's cable internet is notoriously throttled.

Doesn't it depend on the speed of Internet connection?

Here in Canada, chip terminals often show 'PIN OK' - meaning that the local part of the transaction has been completed - within 1 second but then need 10+ seconds to communicate back to the payment processor.

The average time to complete a scheme card transaction is sub 4 seconds on a lowish-latency network. Any extra time is due to the implementation on the merchant side.

Not just in Terminal, but chip and tap in general:

https://squareup.com/us/en/press/square-makes-payments-even-...