Compared to JS, yes, it's slow. You can make Clojure run faster but you will be writing Java with parenthesis not Clojure.
Startup times are indeed atrocious, in Clojure the REPL is obligatory and not optional because of this. You can avoid REPL restarts by using a third party lib like component but you have to buy into a new architecture for your program that can be overkill for many occasions.
Java interop is not a black art but it is painful, the JVM has many great libs but the majority are not, many are loaded with lots of methods returning void, data models like everything needs to a be subclass of an abstract class, etc... So while you can develop with time how to write ad-how Clojure wrappers for your use case faster, you waste lots of time doing it. And yes, this something you have to continually di cause as you said, the ecosystem is very poor.
Without going into the static vs dynamic typing debate, I would say Clojure is at the top of the dynamic languages spectrum (the best in its class if the JVM fits nicely the problem at hand).
Clojurescript's interop with the JS ecosystem is crippled by relying on the closure compiler, which doesn't play well with anything in the JS ecosystem.