What about the huge piece of crap that is the GIL? I mean come on. Clojure is a good reason to care about the JVM. I'd completely given up on the JVM until Clojure landed since there was no great way to tap into it's power without adopting Java's problems. The JVM rocks.
2) can you show some of these results where common lisp is at least 10x slower than java?
But for long-running applications, the performance is very good, and the time it takes to load doesn't really matter. The startup time mostly effects the programmer, who has to start it up to debug the system so often. Clojure sort of mitigates this by having a REPL where you can do testing/debugging without restarting the JVM every time.
All the Java applications that I am required to run are slow, and when they perform well it is because they are using 10x the hardware required by a comparable C++ application.
Of course, if you are creating a network-bound application this doesn't matter much (I can even use Python or Perl for that), but when you want reasonable performance (e.g., on desktop applications), this idea shows to be completely wrong.
Today, developer time is more expensive than CPU time.