I remember when the G5 processor came out a few years ago. After the initial hype died down, people realized that it only had L2 cache whereas the G4 it was replacing had L3 cache. Basically, the L3 cache was a big reason why the G4 was the reliable workhorse it was. The L3 cache made it run that much better.
A similar thing is now being realized with the recently updated MacBook.
According to Geekbench scores (we did a quick Geekbench run through, too), the newest entry level MacBook doesn’t perform as well as the late 2007 models. Reason why? The cache. The new Penryn processor has less cache than the older Merom-based ones. This caveat really only applies to the the entry level MacBooks as the faster clock speed of the higher end ones make up for the smaller cache.
Moral of the story is that this past update was nothing more than a slight, oh-so-slight speedbump. I bought a MacBook 10 days before the new ones were released and didn’t even bother exchanging it for the new one.
MacBook Performance (March 2008) [Primate Labs Blog]