Apple could justify shipping ARM in Macs with the ARM part just being a coprocessor dedicated to JavaScript.

The iPhone XS is faster than an iMac Pro on the Speedometer 2.0 JavaScript benchmark. It's the fastest device I've ever tested. Insane 45% jump over the iPhone 8/X chip. How does Apple do it?! ✨ pic.twitter.com/5nCKZUCAYK

— DHH (@dhh) September 21, 2018