I believe the M1 is much better at computing JavaScript as well. Comparable intel x86 CPUs have 60% more branch misprediction during JS benchmarks and ARMv8.3-A added the processor instruction FJCVTZS (Floating-point Javascript Convert to Signed fixed-point, rounding toward Zero).

Especially due to the better branch prediction, the M1 simply does quite a bit more web browsing with fewer VPU cycles used, thus less power consumption.