Instead of seeing the usual gains of reduced power and raised speeds, Prescott actually worked slower than the previous Pentium 4. Intel had increased the length of the pipeline inside Prescott to make it easier to raise clock speeds in the future. That should have been invisible to outside observers, but we all noticed the performance hit, and none of us could ignore the TDP (Thermal Design Power) which broke past the 100W mark.

Intel responded swiftly by canning development of the 650nm 'Tejas' Pentium 4 and, soon after, by dropping the 4GHz Prescott. It also chose to accelerate development of dual-core processors.

That said, dual- and multi-core processors are definitely the way forward. Unlike Hyper-Threading, using a dual-core processor really is like adding a second CPU to your machine, rather than faking it up, as HT does. You really do have double the processor resources, all the time, not just when there happen to be some execution units going spare.