mruby on the minimal embedded resource

Introducing how mruby comes to term with the embedded board's poor resource.
I suggest a solution that they can mount an external NOR Flash chip as RAM cache.
Although mruby is a minimal implementation of Ruby, it requires huge RAM as is Embed field. A lot of embedded board has poor RAM less than 128KB, except for rich embedded board, like Raspberry Pi.
An external NOR Flash as mruby RAM cache is cheap solution. Typically, NOR Flash's writing frequency is limited, 100 thousand times. I also introduce performance measurement to reduce mruby RAM writting.