The title doesn't do the surprising conclusion justice.
"When we set out to look at how long VMs take to warm up, we didn’t expect to discover that they often don’t warm up. But, alas, the evidence that they frequently don’t warm up is hard to argue with."
By not warming up they refer to instances when early performance is higher than later performance or when the performance doesn't settle.
"When we set out to look at how long VMs take to warm up, we didn’t expect to discover that they often don’t warm up. But, alas, the evidence that they frequently don’t warm up is hard to argue with."
By not warming up they refer to instances when early performance is higher than later performance or when the performance doesn't settle.