Perhaps multi-threaded compression application is good example for scaling:
http://www.techspot.com/review/93-am...ion/page7.html

Q6600 goes from 735 to 1253 (from 1 to 4 cores) - only 70% increase
Phenom 9850 goes from 684 to 1402 scales better - 105% increase
My 9850 at stock speed (2.5Ghz) with ddr2-1066 does 692 / 1951 - 182% increase
(Not sure why mine differs so much from review site...)

Memory is not the reason - single core intel has better score.

Multi-threading is handled a lot better on Phenom. 2.82x increase from 4x cores compared to 1.7x from 4x on Intel Q6600.

This may explain better responsiveness and "smoothness" on phenom - it handles better multiple threads

P.S. Funny explanation from the reviewer for the big difference (ignoring single thread results or platform differencess) - "perhaps using the 100MHz clock advantage"... btw, 2.4 to 2.5 is only 4% difference