> because in many enterprise applications you do not need high performance

Looking at and having looked at some of their cloud spend etc, nah.

To be more specific there's a lot of fat. Whether that's HFT style high performance is a different story.

You can drop cloud spending by 10x factor and still use Spring Boot comfortably. In startup world exist infra costs benchmarks and they are very generous. That fat does not come from frameworks, it comes from not spending an extra hour on solution design.