Another anecdote: in 1990s, Sun servers had relatively "weak" Sparq CPUs, contemporary Intels would wipe the floor with them in integer performance tests. But they had superior interconnect and I/O channels, so e.g. in 4-core configurations Sparq-based servers showed much better application performance (say, running Oracle RDBMS) than the beefier Intel 4-CPU machines.

The connection fabric is utterly important, and expensive.