The Vaio would be far more efficient at running Windows than the Mac would be under bootcamp or as a VM so how on earth is the performance worse?
You should not make such inaccurate misleading statements and pass them off as fact.
The OP did not say a word that he/she wants to run Windows on the MBA.
But here is a fellow member's experience of the MBA on Windows 8:
https://forums.macrumors.com/threads/1606590/
He/she reported to have even better performance on benchmarks and 11 hour battery life.
Either way, if one's planning on buying a mac, it is most logical to assume that that person is going to use OSX.
With your logic, I could argue how the performance and poor system stability of the Vaio Pro under hackintosh.
As for performance, the MBA has HD5000 whereas Vaio Pro has HD4400.
MBA has 802.11ac, Vaio has 802.11n.
MBA has Core i5-4250U or Core i7-4650U, whereas Vaio pro has Core i5-4200U or Core i7-4500U.
MBA got 11 hours of battery life (under Mountain Lion) and Vaio pro got less than 8 hours under light load (Windows 8.1). (According to Anandtech.com)
Of course you can add a sheet battery to the Vaio pro, but that would make it bulkier the the MBA.
I think I am justified to have an opinion that the MBA has a better performance with these supporting evidences. I also believe that "inaccurate misleading statements" is a bit of an hyperbole. At most you could have said that my argument contains confirmation bias as I am only selecting facts that support my argument.
I'll admit that that the Vaio Pro has a great design, very light, thinner than the MBA, and has a better screen, but I strongly believe that the MBA offers more in terms of performance.