Java can compile quickly, a few minutes at most when C++ would take hours, so I am tempted to say that's not a problem.

The startup time is negligible in my experience (few seconds for JVM or python imports). I have to take over slow starting applications from time to time and it's always because of loading data and doing stupid shit on startup, irrelevant of the language. It's not a problem for production because server application only reboot once in forever.

It's still a problem for microservices architectures, unfortunately, especially if you want to support dynamic scaling of some kind. A few seconds is nothing if you expect that your server will be up forever, but it becomes a lot if sometimes it goes down for a bit to move to a different machine, and that takes seconds for your customers.

Also, JIT languages have a very poor habit of doing a terrible first impression because of the warm-up time, especially in Java. If you are delivering applications to customers, that becomes a real burden - the very first time they use your shiny new application, everything is moving like molasses, until the JVM decides it's JIT time...

In a microservice architecture you'd probably have more than one instance running at any given time though, and do a rolling restart so there's always at least one instance available.