Dieter Bohn, writing for The Verge, took the new MacBook for a small test drive. From his writeup:

Apple gave us the 1.2Ghz Intel Core m5 version to test, and though I can notice the difference, it’s small enough that it’s not an easy or automatic upgrade from the previous MacBook. I ran a few benchmark tests and have been poking around for the last twenty minutes or so — nothing too crazy — and here’s the long and short of it. Geekbench 3 pegs the speed improvements on raw processor operations at around 20 percent, but disk-write speeds using Blackmagic saw bigger improvements, as much as 80 or 90 percent faster (reading speeds look like smaller, incremental improvements). Overall, the thing feels about 25 percent faster to me.

Dieter tested the faster of the two new models (the other is 1.1Ghz). Apple advertises this model with a Turbo Boost up to 2.7GHz. My understanding is that Turbo Boost is an overclocking mode that automatically kicks in (not something you can control) when the processor gets loaded.

For comparison sake, the high end MacBook Pro has a 2.9Ghz processor with a Turbo Boost up to 3.3Ghz. That’s about a 13.7% boost, compared to the new MacBook’s huge jump from 1.2Ghz to 2.7Ghz Turbo Boost, a rise of 125%. Someone check my math on this.

Obviously, the MacBook Pro starts at a much higher clock speed, so perhaps the big rise is due to a much lower starting point. But still, that’s a big difference. And looking at my shopping cart, I see that for an extra $150, I can upgrade to a 1.3Ghz processor with a 3.1Ghz Turbo Boost.

I do wish there was a 16GB option.