Xfiles is an interactive utility for comparing and merging one file tree with another over a network. It supports freeform work on several machines (no need to keep track of what files are changed on which machine). Xfiles can also be used as a cross-validating disk<->disk backup strategy.
java performance - superstition vs. real numbers
People who make comments about java's performance generally reveal in the process that they've never used java, or at least not in the last few years.
Benchmarks show java as being in the same ballpark as C across multiple types of computation (integer, floating point, etc.). Perl is fast at only one thing: strings -- try doing floating point in perl (really, try it).
See e.g. the java-vs-C benchmark page at www.idiom.com/~zilla/Computer/javaCbenchmark.html,
or search on Tom's hardware for a similar benchmark.