[icambron]

You may know this, but maybe it's worth pointing out that the big savings here is actually just that the function itself can be pretty expensive, since it may stringify some data structure. In eagerly evaluated languages, if you say this:

    log("debug", "I found: " + foo.toString());

you end up doing a lot of work to create that string, only to have it be ignored by the log call. Whereas if you say:

    log("debug", => "I found: " + foo.toString());

any extra assembly you execute (or generate) to make that work is peanuts compared to avoiding the call to toString(). None of that (besides the simple thing of log levels) helps with the OP's problem with IO, but it can make a real difference to your CPU.