As I watch avh's GifRobot chug along with -verbosegc, async GC seems to
be running too frequently. The robot seems to wait quite a bit for something
or another, and during that time async GC runs again and again, typically
getting no memory back. This isn't a problem as far as WebRunner is concerned,
but other processes on the machine might have better things to do. Async GC
should be a little smarter about deciding when to run.