For the last few years I’ve been using a 2015 MBP with a 2.7GHz processor. I recently got the 2018 MBP with touchbar and only just noticed it was a 2.3GHz processor (oversight on my part). I looked into it because I was playing Civilization 6 and it keeps crashing when plugged into an external monitor.
Has Apple really created a more expensive, less powerful machine than the one from 3 years ago?
See MacBook Pro Performance (July 2018) for one analysis of the CPU and GPU performance improvements in the 2018 models. The linked full Mac performance results have both updated numbers and comparable results from the 2015 machines.
Note that the I/O speeds have also increased significantly in MBPs over the last few years.
You’d get a better take on how well the new MBPs work for you by measuring them with your workload.
Related factoid: The fastest Mac on their multicore benchmark is also “only” clocked at 2.3GHz. Yeah, yeah… It’s an iMac Pro. Still, it’s a demonstration that a single number like CPU clock rate isn’t a very good estimate of performance.