That's interesting. Do you have a public source for this handy?
I remember seeing an article [1] proclaiming that more than 50% of Azure's workloads are on Linux, so I'm guessing their hypervisors are running an optimised Linux kernel somewhat.
1: Linux is Most Used OS in Microsoft Azure – over 50 percent of VM cores
https://news.ycombinator.com/item?id=23156222