@lefticus I just got some cycles to recompile chaiscript with thread support. Performance improve is at least 10x on VS 2013. It is mind blowing. I do use multi threading but I create my own instance of chai for each (maybe not the best way, but this is only for a non interactive optimization use case, so doesn't matte if it hogs memory and cpu). Making it thread safe by design.
without thread support*
I would encourage you to release without thread support, just for the perf gains