Sluggishness was a consistent gripe with two prior versions of the MacBook Air, especially compared to the rest of the MacBook line. The latest version has speedier processor options, but according to recent benchmarks, might have gotten slower. Huh?
In their review of June's upclocked, marked-down MacBook Air, MacWorld noticed some odd benchmark results. Compared to the Late 2008 MacBook Air, clocked at 1.86GHz, the new top-end model, clocked at 2.13GHz, couldn't quite keep up. This is odd, since the rest of the specs have remained basically static, and the only difference between the processors is clock speed.
Confirming their suspicions, they found the June 2009 1.83GHz Air to be markedly slower than the Late 2008 1.83GHz model, despite nearly identical specs. So, what the hell?
The obvious answer here would be some kind of firmware change, since it doesn't make sense from a hardware perspective. MacWorld speculates that the newer Airs could have more aggressive thermal management features, which throttle the processor when it gets too hot—a theory somewhat supported by the fact that high-stress benchmarks showed a proportionally greater performance decrease than easier ones.
Another possibility in the same vein: Underutilising faster processors simply gives Apple better power consumption and heat results. Problem is, that doesn't explain why the matched processors perform differently. Also, Apple's whole pretense that the new Airs are faster than the old ones would have been a intentional, egregious lie.