L2 size, L2 speed, whatever, they're both down to the goodness of the SoC design, not the ISA. For that matter, the 20% difference you found could be compiler

L2 size, L2 speed, whatever, they're both down to the goodness of the SoC design, not the ISA. For that matter, the 20% difference you found could be compiler maturity. And it's small enough that it's hard to notice without sitting two machines doing the same thing next to each other, or using a stopwatch. But yeah, could well be that TH1520 has a duff L2 cache design in some way. Much more shocking to me than the Pi 4 beating the TH1520 by 20% is the in-order dual-issue, 20% slower clock speed JH7110 beating it by 13% on a GNU toolchain build.