I would say Tim Bray is making an amazing effort to tackle the hard problem of optimizing a language that he has even at this point only passing familiarity. That said, it's great to have such a well known hacker try to put Clojure through it's paces.
Having optimized my fair share of Clojure programs it's certainly possible to get very close to Java speeds. Also in my experience there's often a point of diminishing return. It's often simpler to just write that tight loop in a tiny Java class and be done with it. Just as Python is extensible in C when you need performance, Clojure is extensible in Java.
With the work in the Clojure new branch, the possibility of writing wicked fast Clojure in Clojure is just around the corner.
I work in Python and JavaScript day in and day out and my comparisons follow:
I can say without a doubt, idiomatic Clojure (not heavily optimized) is generally faster than Python, and more elegant IMHO. Once you get used to pretty much everything returning a value, Python can drive you insane. The only thing I generally miss about Python is that's more usefulf/friendly as a command line scripting language. But for building an app, Clojure all the way.
I use JavaScript even more, and Clojure has all the things I like about JavaScript except even more flexible and useful in contexts other than web programming (OpenGL programming for example). I picked up Clojure precisely because I wanted a fast elegant dynamic and concurrency ready programming language.
As the JDK evolves and our laptops start having 4 cores, I think the case for Clojure will only grow.
Having optimized my fair share of Clojure programs it's certainly possible to get very close to Java speeds. Also in my experience there's often a point of diminishing return. It's often simpler to just write that tight loop in a tiny Java class and be done with it. Just as Python is extensible in C when you need performance, Clojure is extensible in Java.
With the work in the Clojure new branch, the possibility of writing wicked fast Clojure in Clojure is just around the corner.
I work in Python and JavaScript day in and day out and my comparisons follow:
I can say without a doubt, idiomatic Clojure (not heavily optimized) is generally faster than Python, and more elegant IMHO. Once you get used to pretty much everything returning a value, Python can drive you insane. The only thing I generally miss about Python is that's more usefulf/friendly as a command line scripting language. But for building an app, Clojure all the way.
I use JavaScript even more, and Clojure has all the things I like about JavaScript except even more flexible and useful in contexts other than web programming (OpenGL programming for example). I picked up Clojure precisely because I wanted a fast elegant dynamic and concurrency ready programming language.
As the JDK evolves and our laptops start having 4 cores, I think the case for Clojure will only grow.