Firstly, both of those processors are much older than two years, they're closer to a decade old now!
Remember: The Intel® 'Core™2 Duo' is +116% more powerful, clock for clock, than an Intel® 'Pentium® D'!
- As in +16% more than twice as fast!
This is why the Athlon 64 X2's were so popular, back in their day
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http://www.anandtech.com/show/2045/16
- AMD's budget CPU outperformed Intel's best CPU
Needless to say Intel has learned from that, the current Core i3/i5/i7 extend that lead even more.
- The Core i7 has a better 6th++ generation implementation of SMT/HyperThreading.
The Pentium D gains from it heaps, in non-HT software it's performance per clock was pretty dismal.
- Not enough for any post 2007 game though...
Today's games are optimized using a compiler that creates machine code that targets the Intel Core i3/i5
- The code created wouldn't run very well on a Pentium 4 era CPU, which is all the Pentium D with HT is, two Pentium 4's glued together.
- In fact it may even execute more slowly than compiled code that targeted a stock 6th gen CPU.
All of the old CPU's, excluding the AthlonXP/MP+, lacked issue width, they were not super-scalar like today's processors are.
- In fact AMD has probably LEAPED backwards in x87/SSE performance with it's fake 8 core processors.
- They were super-scalar, just no-where near as super-scalar as the Core i3/i5/i7.