On Mon, Sep 28, 2015 at 9:08 AM, Will Sewell <me@willsewell.com> wrote:

If it is the GC, then is there anything that can be done about it?

Increase value of -A (the default is too small) -- best value for this is L3 cache size of the chip
Increase value of -H (total heap size) -- this will use more ram but you'll run GC less often
This will sound flip, but: generate less garbage. Frequency of GC runs is proportional to the amount of garbage being produced, so if you can lower mutator allocation rate then you will also increase net productivity. Built-up thunks can transparently hide a lot of allocation so fire up the profiler and tighten those up (there's an 80-20 rule here). Reuse output buffers if you aren't already, etc.