> As I recall it, Intel brought about Hyperthreading on Northwood and later Pentium 4s as a way to help with issues in it's long pipeline.

Well, Intel brought Hyperthreading to Xeon first and they were quite slow, so the additional thread performance were quite welcome there.

But the GHz race was lead to the monstruosity of 3.06GHz CPUs where the improvement in speed didn't quite translated to the improvement in performance. And while the Northwood fared well (especially considering the disaster of Willamette) GHz/performance wise, the Prescott wasn't and mostly showed the same performance in non-SSE/cache bound tasks[1], so Intel needed to push the GHz further which required a longer pipeline and brought even more penalty on a prediction miss.

Well, at least this is how I remember it.

[0] https://en.wikipedia.org/wiki/List_of_Intel_Xeon_processors_...

[1] but excelled in the room heating, people joked what they even didn't bother with an apartment heating in winter, just leaving a computer running