I mostly disagree with the conclusion. GC can be very fast these days. Serialization to JSON does not really take much time. Granted, some scripting languages are terribly slow.

But the main problem seems to be a lack of a clear architecture in many systems. These systems have often accumulated so much technical debt that nobody understands why they are slow. Profiling and optimization might remove the worst offenders but usually don't improve the architecture.

Basically, in the software industry, we use the hardware gains to cover up our organizational deficits.