It's very subjective, for sure. I've always felt like browsing on Apple silicon (M1/A# Bionic) is "snappier" than on its counterparts, but it's hard to quantify. Speedometer has successfully put that into numbers, so that number is relevant to me.
The 5600X and M1 scores seem quite significantly lower than what I’ve found but the overall trend holds true in that the single thread performance of the A16 Bionic beats all but the highest end X86 CPUs. WebKit also plays a bit of a role, accounting for something like 20% difference on the same device for this specific test. Also this isn’t the latest version of Speedometer there is a 2.1 now so anyone trying it out be careful you use the same revision as newer ones perform faster (I assume they use newer versions of the libraries named in the test which are more optimized over time).
While it is true that Speedometer is developed by Apple, it feels misguided to just throw in "of course it will be performant". Even Google Chrome scores higher in Speedometer in M1 (184, vs 88 when ran on an Intel Mac) -- so it's not like Apple is just underhandedly making its own software score higher. To be fair though, it's not like you can test other browser engines on an iPhone since they're all just basically Webkit web views.
Also it's worth noting that on Basemark Web 3.0, the iPhone 14 Pro Max scores 1033.56 while the formidable Galaxy Z Fold 4 running the SD 8+ Gen 1 scores only 641.02, so it doesn't appear like Speedometer is just fluffing numbers for Apple.
Is there a benchmark for sustained performance? Its my understanding that mobile platforms aggressively throttle for thermals, and so they can provide a burst of performance but then dial it down.
For most users, burst performance is more important - you want to load an app as quick as possible, but then the CPU will be mostly idle while you navigate the menus of the app...
If you want to assess how well a particular CPU behaves comparing to others you need many different benchmarks.