Charles Nutter published a post on how various languages can be optimized on various virtual machines. He's one of the few people knowing a lot about compilers and about how to compile a language to different virtual machines. If you like to learn about the low-level stuff (you can almost hear the CPU registers working while reading the article :)), it's an interesting article about the influence of a language's type system to the optimization the JVM can perform. In other words, how fast the program can run.
Follow the link to read Charles Nutter's article: On Languages, VMs and Optimization