In exchange for dramatically lighter weight and an extremely thin profile, Apple has definitely compromised when it comes to the MacBook Air's tech specs. And the results of Macworld Lab's preliminary tests of the MacBook Air reflect those compromises.

For this first set of tests, we used a default-configuration MacBook Air powered by a 1.6GHz Intel Core 2 Duo processor with a 4200rpm, 1.8in 80GB parallel ATA hard drive. The MacBook Air's processor clock speed lags well behind current MacBook (2.0GHz or 2.2GHz) and MacBook Pro (2.2GHz, 2.4GHz, and 2.6GHz) models, and its hard drive is also slower than those used in the other models.

Our tests reveal that the slower processor and disk make the MacBook Air quite a bit tardier than the other portables in Apple's product line. The MacBook Air was also outpaced in our tests by its closest desktop cousin, the ultra-compact 1.83GHz Mac mini Core 2 Duo.

Although none of our test results seem horribly out of whack with what one might expect from the MacBook Air given its modest specs, it's necessary to provide some caution for these preliminary numbers. Testing a brand-new piece of Apple hardware is always a challenge, usually introducing wrinkles into our test procedures that require us to carefully plot out the best way to test a system.

In the case of the MacBook Air, we discovered that one of our base assumptions - a series of tests involving startup and data loading over an ethernet network - might be an issue with this system, which can connect to wired ethernet networks only via a £19 add-on USB adaptor.

We've tested the system with and without the adaptor, and will continue to investigate any effects the MacBook Air's unique networking characteristics might have on our tests.

Similarly, one of our base tests - encoding an H.264 movie from DVD using HandBrake - requires the use of an optical drive. For this test, we used Apple's optional £65 USB SuperDrive. And now that a Mac exists with no built-in ethernet or optical drive, we'll have to re-evaluate our use of those tests when we build the next update to our Speedmark test suite.

In the meantime, keep in mind that we will continue to test the MacBook Air as well as reference systems, and as a result future test scores for these systems may vary from what's reported here.

Speaking of Speedmark, the MacBook Air's score of 123 is the lowest score we've recorded for any Intel-based Mac laptop, but it does handily beat our PowerPC laptop reference system, the 1.67GHz 15in PowerBook G4.

Of course, the MacBook Air's appeal is not about blazing speeds, but about small size and weight. However, these tests do give some indication about what level of performance users will have to give up if they've decided to forego a MacBook or MacBook Pro for the thin embrace of the MacBook Air.

Macworld's Macbook Air Test Results