Since the introduction of Opteron at the beginning of 2003 until the introduction of Core 2 at the middle of 2006, the AMD CPUs were vastly superior to any kind of Pentium 4, not only to Pentium D.

This was much more obvious in servers or workstations than in consumer devices, because the kinds of applications run by non-professionals at that time were much more sensitive to the high burst speeds offered by Pentium 4 with very high clock frequencies, than to the higher sustained performance of the AMD CPUs.

In 2005, I had both a 3.2 GHz Pentium 4 (Northwood, 130 nm) and a 3.0 GHz Pentium D (Prescott, 90 nm). With any of them, the compilation from sources of a complete Linux distribution took almost 3 days of continuous work of 24 hours per day.

After I bought an Athlon X2 of only 2.2 GHz, the time for performing the same task has been reduced to much less than a day. Even for some single-threaded tasks, but which contained many operations that were inefficient on Pentium 4, like integer multiplications or certain kinds of floating-point operations, the 2.2 GHz AMD CPU was several times faster than the 3.2 GHz Pentium 4.

At work, the domination of the AMD CPUs was even greater. Each server with Opteron CPUs that we bought was faster than several big racks with Sun or Fujitsu servers that were used before. Intel did not have anything remotely competitive. At the beginning of 2006, on my laptop with an AMD Turion I could run professional EDA/CAD programs much faster than on the big Sun servers normally used for such tasks. Intel had nothing like that (i.e. the 32-bit Intel CPUs could not use enough memory to even run such programs, so the question whether they could have run such programs fast enough was irrelevant).

Of course, half of year later the competition between Intel and AMD looked completely different.