Windows 10 on MacBook Air
It depends on how you run Windows and the amount of RAM you have in your Macbook Air (4GB or 8GB)

If you're running Windows through virtualization software like Parallels Desktop or VMWare Fusion, indeed expect performance issues.  The system has to run 2 OS'es and definitely on a 4GB Macbook Air this might require some serious disk swapping (granted, swapped to a quite fast SSD indeed).

However if you're talking about Bootcamp, I'd expect quite the opposite: it'll run better on your MacBook than on a similar spec'ed PC laptop.
Apple has done a great job on supplying the correct hardware drivers and your system will probably run like a charm - even with the 4GB version.

As you know 'Ask Different' is a Apple oriented stack, and it will be difficult to find people - including me -  endorsing it.

You might be one of these 2 types of users:

Type 1.
You've worked on Windows for your whole life and, while you love the outer design of the Macbook, you don't feel ready to move to OSX.
Today, most of the software available on Windows has similar solutions available on OSX.
I've been there. and strongly suggest you do the same as I did.  Go for OSX, cold turkey.  It will feel awkward first, but I promise you won't regret it.  Risk is high you're going to hate Windows later.

Type 2.
You're working on OSX but you need software not available on OSX.  In our organisation we do have Macs equiped with Windows via VMWare Fusion just because there are no alternatives:


ArcGIS: while we use QGIS on OSX internally, we still need ArcGIS because our partners use it.
Specific analyzing/flashing/config &amp; maintenance toolsets for certain hardware
Specific webbased tools only available for Internet Explorer (certain java tools and ActiveX components)
Chances are low any of these will ever be available under OSX but the day they are available, VMWare will go, that's for sure.