I have some silly preference against JRuby.  For some reason I don't
like java, and it's a purely aesthetic dislike.  Not even anything to do
with the look of the language!

I did test JRuby out though.  I'm using a perlin noise gem that's been
built as a c extension, and it's quite fast.  Unfortunately it didn't
work with jruby, and a jruby compatible gem was significantly slower.  I
need this speed, and don't want to rewrite it myself in java (if that
turns out to be fast enough anyway).

I have heard that GC is improved in ruby 2.0.

>You will of course need to refactor, but the result will be better,
> and you will learn a lot in the process.

This I think will be very true!  I need to learn how to profile the
Garbage Collector, and find out the hotspots where I'm doing a lot of
objection creation and deletion.

I have heard a rumour that using for-in rather than .each involves more
object creation and deletion, but I don't know if that's true.  It will
be one of the things I'll be testing to see if it helps improve
performance.

> Is it really the
> number of garbage to collect which makes things slow or maybe low
> memory leading to paging

I think your suggestion here is that system memory is running out, so
garbage collection is using a hard drive based swap file.  If that's
what you mean, I suspect that's not the issue since I have 8GB memory on
my system, my app seems to use < 500MB right now, and I don't think I
have enough unrelated loaded apps.  I'm on mac os x and 'free' doesn't
seem to work to tell me memory usage, so I can't be sure :)  I will keep
this in mind though.

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