Processor Specifications

[Platypus]

As a comparison, I went from a 2.8GHz P4 to a Core Duo 1.8GHz (that's the original Core, the current Core2 has more performance for same clock speed). It's noticeably faster than the 2.8GHz P4.

The article CCT linked to is quite good.

Basically there are 3 ways to increase a processor's performance:

Clock speed - simple, instructions execute faster, it's faster. But it's not as simple as it sounds, there are complications.

Execution efficiency - this is the complication. Sorting out the things that stop a CPU from achieving the potential from its clock speed. Caching, pipelining, branch prediction/prefetch, data transfer...

Parallel processing - more than one execution unit means more instructions are executed in a given time, therefore it's faster.

The P4, due to design decisions at Intel, utilised the high clock speed philosophy, but its execution efficiency was not very high. Core uses lower clock speeds but has higher execution efficiency, so even the Core Solo CPUs give relatively good performance. But of course Duo gives much more punch in many applications (including just the running of Windows itself, or another modern OS).