[acdha]

One great example of this was back in the P4 era where Intel hit higher clock speeds at the expense of much higher latency. If you made a binary for just that processor a smart compiler could use the usual tricks to hit very good performance, but that came at the expense of other processors and/or compatibility (one appeal to the AMD Athlon & especially Opteron was that you could just run the same binary faster without caring about any of that[1]). A smart JIT could smooth that considerably but at the time the memory & time constraints were a challenge.

1. The usual caveats about benchmarking what you care about apply, of course. The mix of webish things I worked on and scientists I supported followed this pattern, YMMV.