I suppose these guys just don't apply the patch. They are not running in a public cloud with potentially hostile neighboring VMs; they run their own trusted code. They might choose to tighten perimeter security instead, in the short term.

Meltdown is aptly named, as that is what's gonna happen to the global corporate services market, "efficiently" hosted in the cloud and scraping for profitability.

For pure computational cases Meltdown vulnerability remediation might not impact you as much. Meltdown fixes would affect applications that do a lot of syscalls - lots of socket IO, IPC stuff, small and frequent disk IO ops etc.

You'll probably see a wide variety of benchmark results anything from no impact to things like above. So just make sure you measure carefully with your own workload.

Data processing where number crunching is the key problem may not be affected much. Data processing where fetching and assembling the data from many sources is likely to see larger slowdowns. Pure communications workloads are also likely to see larger slowdowns.