Apple has released a macOS High Sierra 10.13.6 Supplemental Update for all compatible Mac devices. The company says that the latest update is specifically designed to improve the "stability and reliability" of the updated MacBook Pro models that debuted earlier this month. It is reported that the update fixes the CPU throttling seen on Intel Core i9-powered MacBook Pro 2018 laptops that was speculated to be caused by a thermal issue. Apple says the CPU throttling was caused by a missing piece of firmware code that affected the thermal management system. YouTuber Dave Lee had first demonstrated the flaw in a video that showed how the video editing on the Core i9 model of the MacBook Pro 2018 was taking more time to render content compared to the Core i7 variant of the 2017 MacBook Pro. The CPU clock speed was found to have been throttled, findings that had been confirmed by multiple publications.
"The macOS High Sierra 10.13.6 Supplemental Update improves the stability and reliability of MacBook Pro with Touch Bar (2018) computers and is recommended for all users," Apple has said on its support page.
An Apple spokesperson in a statement to CNet has additionally confirmed that the latest macOS update comes after extensive performance testing and adds a digital key to the firmware to fix the thermal management system and ultimately enhance the performance of the new MacBook Pro models. "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 Supplement Update and is recommended," the spokesperson said, adding that customers can expect the new 15-inch MacBook Pro to be up to 70 percent faster, and the 13-inch MacBook Pro with Touch Bar to be up to 2x faster, as shown in the performance results on Apple's website. The CPU throttling issue affects both new 15-inch and 13-inch MacBook Pro 2018 models, CNet notes.
As demonstrated by YouTuber Lee, while the Core i7-powered 2017 MacBook Pro model had taken 35 minutes and 22 seconds to render a clip, the Core i9-backed 2018 MacBook Pro had taken about 39 minutes and 37 seconds to render the same file. This was apparently due to the thermal management bug that was restricting system performance on the new models. "This MacBook can't even maintain the base clock speed. Forgot about the Turbo [Boost] and all that stuff, it can't even maintain the base clock of 2.9[GHz], which is absurd," Lee had said in the video.
Notably, Apple issued the latest macOS update less than two weeks after launching the new MacBook Pro models. The security content of the new update is yet to be revealed on the Apple support site.
You can download the fresh macOS High Sierra 10.13.6 Supplemental Update on your Mac device by going to the App Store and then visit the Updates section. Once you reached the Updates section, click the Download button and then enter your Apple ID credentials in the provided box to begin the download process. After the download process accomplished, an information window will come in front of your screen, click on Continue and then wait until the update automatically installs on your device. You can also use this link from your macOS machine to begin the download process. The update package is 1.31GB in size.