https://www.techradar.com/news/apple-solves-macbook-pro-2018-throttling-issue-with-software-patch

Following a week of getting dragged on YouTube and Reddit for a performance throttling issue, Apple’s new MacBook Pro 2018 is now rid of the problem through a software patch. Apple issued a statement regarding the issue and its new fix, Laptop reports.

“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.”