Benchmarks in general are meant to give an unbiased comparisons of a machines performance. But benchmarks are not always a realistic indicator or real world performance.
If you take a look at Xbench results (or many other benchmark utilities) you will see what looks like a huge variation in results in machines that seem to have identical hardware configurations.
There are a number of potential causes for this - identical hardware actually performing differently, impacts of hardware not enumerated by the benchmark, and the impacts of software and configuration not enumerated by the benchmark. Many benchmarks are extremely sensitive to programs and utilities you may have running in the background or the state of the machine (freshly booted or been running for three weeks) when you run the benchmark.
The bottom line is that often benchmarks are only useful as a very rough gauge when comparing and you have to realize that even if you optimize your machine to "score" better on a particular benchmark, that does not necessarily translate to any real world gain for your use.
So if you are happy with your machine's performance, don't worry about it. And if not, there are often things you can do about particular issues, so keep asking.
The MBA HD has some significant performance limitations and its never going to be a stellar performer, but there are things you can do to mitigate it.
a) Xslimmer gives you a big immediate boost for a frequent activity
b) Cocktail will roll over log file and clear caches that will prevent a slow performance decline over time but is not a big immediate boost for a machine only a few weeks old.
c) iDefrag will place frequently accessed files on the sweet spot on your disk, optimize system files and OS resource files but its not something most will benefit from more than a couple times a year and is best run after a month or so of getting your machine set up the way you like. At that point you may get a significantly improved boot time and some operations may seem a touch faster but its not like Xslimmer.
d) You could try a utility called SmartSleep to potentially save you a couple more gb of disk space and sleep much faster (provided you don't tend to let your battery run dry while sleeping)
e) There's a utility called iFreemem that monitors memory usage and allows you to clean up unused memory manually before doing something significant like starting up a virtual machine on a MBA.
f) There is another utility called Bokah that lets you adjust job priority so all your cpu can be focused on a particular foreground application or you can force individual jobs to a lower proprity so they don't impact your foreground.
I've tried all of these and they work well to some extent but OS X does pretty well on its own for the most part and investing the time and money in these utilities is not for everyone. Also, it only helps to tweak an area you are having trouble with. Many may have trouble with the MBA's HD performance but fewer will likely encounter issues with memory and CPU.
