It's not just Adobe Premier. If you run Prime95, it starts throttling almost instantaneously and drops well below 2.9. Prime95 keeps CPU load at about 98 - 99 percent. In my somewhat perfuntory testing, it oscillates between 2.2 and 2.5, sometimes dropping even below 2.2. And this is without involving the dgpu. Premier hits the processor to the max, and it leverages dgpu, which heats things up even more. Apple "pro" apps simply don't push the CPU hard enough to flesh out the disgraceful degree to which the i9 chip throttles in Apple's sexy svelte chassis.
So the disconnect here is the definition of thermal throttling. Dave2D's review was excellent, comprehensive, and unbiased. As an example of a clueless approach to things, iJustine just did a review of her new $7,700 MacBook pro. She tried to perform a throttling test. In her test, the CPU utilization never reached more than 40 percent. She also put her 2016 and 2018 laptops in her refrigerator, apparently because her audience suggested she do that. She was clearly confused by the process and the results, but she did clean out her fridge.
I also have MacBook Pro retina mid 2015. When prime95 runs, the CPU never drops below 2.6 GHz, which is 100 Hz higher than the base clock. When running other CPU intensive tasks, e.g., Handbrake, the CPU stays around 2.9 - 3.0 GHZ.
Per my earlier messages, Apple can offer a palliative in the form of a firmware update. Where less fan noise will be traded for better performance. I am pretty sure that by making the fan curve more aggressive then can at least keep the i9 around 2.6 - 2.9 GHz under full CPU load.
