Interactive latency. Being able to type and have it appear on the screen instantly, reliably.

> Decent PC or Mac with SSD is much faster than iPad

Yes, but speed isn't latency and hardware speed is irrelevant.

My DOS-based 286-12 had better latency than my Surface Book and MacBook Air do, mainly because DOS has no (or very little) multitasking. My iPhone also has excellent latency as it limits the APIs available to background tasks, stopping the typical 'Windows Search Service' (or any other random background executable) killing foreground performance.

I'm sorry I haven't use Windows for a while but there latency, as you call it, is much better on Linux/MacOS based machines than on iOS. Switching between windows without waiting, multitasking all those, and more, things are much better on computer.

You should look at benchmarks of latest iPad Pro vs. Mac laptops. iPad Pro is faster than lower end Mac laptops and only a little bit slower than MacBook Pros.

Only in benchmarks. Look at the workflow presented in article. There is no builds required nor CPU heavy processing. But there is a lot of switching between applications, multi windows etc. iOS UI is not prepared for this kind of workflow. Even the newest improvements on iPad Pro are far away from being as useful and as fast as on normal laptop.

Sorry, I misunderstood you. The way you phrased your earlier comment ("Mac with SSD") made me think you were talking about hardware performance.

On macs with without SSD UX is lagy

Why does graphics performance matter for programming? (Game design excluded of course)