For a week, we have been seeing reports that the newly released MacBook Pros run hot, which all kicked off after this video by Dave Lee. They run so hot, in fact, that the very fancy 8th Gen Intel Core processors inside them were throttled down to below their base speed. Apple has acknowledged that thermal throttling is a real issue caused by a software bug, and it’s issuing a software update today that is designed to address it.

The company also apologized, writing, “We apologize to any customer who has experienced less than optimal performance on their new systems.”

Apple claims that it discovered the issue after further testing in the wake of Lee’s video, which showed results that Apple hasn’t seen in its own testing. In a call with The Verge, representatives said that the throttling was only exhibited under fairly specific, highly intense workloads, which is why the company didn’t catch the bug before release. The bug affects every new generation of the MacBook Pro, including both the 13-inch and 15-inch sizes and all of the Intel processor configurations. It does not affect previous generations.

“There is a missing digital key in the firmware that impacts the thermal management system.”

Here’s the company’s statement, in full:

Following extensive performance testing under numerous workloads, we’ve identified that there is a missing digital key in the firmware that impacts the thermal management system and could drive clock speeds down under heavy thermal loads on the new MacBook Pro. A bug fix is included in today’s macOS High Sierra 10.13.6 Supplemental Update and is recommended. We apologize to any customer who has experienced less than optimal performance on their new systems. Customers can expect the new 15-inch MacBook Pro to be up to 70% faster, and the 13-inch MacBook Pro with Touch Bar to be up to 2X faster, as shown in the performance results on our website.

Apple declined to provide more detail on what precisely this “missing digital key” is — beyond the fact that its lack impacts the thermal management system. The company is sticking to its stated performance claims on the new machines, and it will add one more benchmark graph to its official MacBook Pro page on its website to reflect more recent tests.

The admission caps off a full week of drama over these new MacBook Pros. Surprisingly enough, thermal throttling is not the main storyline in this drama. That role falls to the keyboard. Apple persists in insisting that the redesign of the keyboard to include a silicone barrier was to make the keyboard “quieter.” It does so in the face of its own internal documents that state plainly how the new design should help its keyboards be more reliable when crumbs or grit make their way inside.

“We apologize to any customer who has experienced less than optimal performance on their new systems.”

As for the throttling drama, making sense of the various articles and videos benchmarking these machines has been nothing less than head-spinning, and making sense of all the differing results has been a challenge. Here’s a couple, though: Jonathan Morrison ran an extensive battery of tests that show the i9 MacBook Pros to run faster than the i7. On the other hand, the founder of Geekbench created some custom tests that showed that the top-end i9 processors performed slower:

I’m working on other tests, and some show the i9 is faster than the i7. For example, in just about every single-core test (burst or sustained) the i9 is faster than the i7. I’ll hopefully have something to share with more detailed tests (and more data!) next week. — John Poole (@jfpoole) July 20, 2018

Now that there’s a software fix that puts the so-called “missing digital key” back in to better manage the temperature of the processors, it looks like everybody will need to run those tests all over again. That’s precisely what we’re going to do ahead of our review.

We’ve also reached out to Intel and will report back if they have comment.