[arnehormann]

This is too late to help you, but still...

BitSets: look at math/big - not that intuitive, but what you need is probably there.

Sets: I wrote https://gist.github.com/arnehormann/6234573 while thinking about an api. It's not a regular repository because I never needed a set type myself, but it should work.

Like another commenter said, the cpu usage statistics in the Java program are most likely due to Java threads you didn't start yourself, e.g. the garbage collector. If your code involved creation and disposal of a lot of Objects, Go is at a serious disadvantage compared to the JVM. But that can be mitigated with a little effort and will probably disappear in due time.

[kisielk]

I actually wrote a bitset implementation using math/big: https://github.com/kisielk/bigset