But to make a fair comparison, one would have to throttle the memory to the speed of a 2004 memory chip. Then
the CPU single core performance increase will be a lot less. Also the Pentium 4 architecture was a crossroad and Intel switched back to Pentium 3/M for Core. So a better comparision is the fastest Pentium M with a modern Core CPU.
This isn't true. There's easily a single thread win, clock-for-clock, of 2-3x over this period.