Dave Lee posted a new video this afternoon about the Core i9 MacBook Pro he bought, and after testing, the new machine can not even maintain its processing power, like video editing, in a short time.
"This CPU is a non-locked, overclockable chip, but all the CPU potential is wasted in this chassis ̵
He shares some Premiere Pro render times, suggesting that the new 2018 MacBook Pro with Core i9 chip performs worse than a 2017 model with Core i7 chip. It took 39 minutes for the MacBook Pro 2018 to render a video that could render the older model in 35 minutes. Premiere Pro is not well-optimized for macOS, but the difference between the two MacBook Pro models is remarkable.
Lee performed the same test again with the 2018 MacBook Pro in the freezer, and in cooler temperatures, the i9 chip was able to deliver outstanding performance, reducing render time to 27 minutes and beating the MacBook Pro 2017.
As Lee points out, thermal throttling is in no way uncommon, and it is seen in a variety of laptops and mobile devices by a number of manufacturers, but he says that "this degree" thermal throttling is "unacceptable"  This type of thermal throttling really concerns the end user. It does not matter what you use it for, like if you're a Final Cut user or an Adobe Premiere user or if you use it for software development or calculations like fluid dynamics – it does not matter what you do with your Make device. If you have some sort of advanced computation that the CPU uses – that's probably why you're considering these devices at all – it'll slow you down. And that is unacceptable to me.
It's not clear if something is wrong with the MacBook Pro with the Core i9 chip that Lee got, because this throttling is probably something Apple would have tested for, not something that other users have reported Point.
Since this is just a data point, the information is not sufficient to make a statement about the i9 chip available for the 15-inch MacBook Pro, but further testing will certainly bring more light into Lee's video.