The new Dell Inspiron 17 7786 can run 20 percent faster than the last generation Inspiron 17 7773 for the first 10 to 20 minutes before clock rates begin to dip dramatically. At that point, CPU performance stabilizes at 10 percent slower than the older Core i7-8550U CPU. This "delayed" throttling behavior is uncommon on many laptops.
https://www.notebookcheck.net/Unusual-throttling-behavior-shows-the-Core-i7-8565U-running-both-faster-and-slower-than-the-i7-8550U.403236.0.html
Interesting... if you make the assumption that most non-gaming stress loads will be less than 20 minutes in length the new CPU provides a substantial performance bump of around 20%. But if you have long sustained loads your going to get less out of it than the 8th gen.