CPU performance throttling

My laptop is a 6-year old Thinkpad T460s. Recently, I am looking for a new laptop, and I still prefer Thinkpad. When reading many laptop review articles on the internet, I noticed that CPU performance is likely throttled under the heavy workload because of the heat, especially Intel CPU. That happens easily.

Throttling means "limit the CPU performance". That also imples if you buy a Core i7 CPU, but you usually can't get the expected performance. It's something like your Core i7 is actually downgraded to Core i5. It's kind of unacceptable. If so, does that mean it's not worthy paying more money to buy a laptop with so-called high performance CPU (P-series and the H-series)? Or we should go for U-series?

Additionally, if AMD CPU can perform better in terms of the throttling issue? (Considering AMD CPU is made by 5nm or 6mn manufacturing process. Intel 12th gen CPU is 10nm)