strange real timings partly explained

[Henry Cejtin]

I'm  a bit nervous about just aligning all objects mod 8.  For one thing, you
would have to re-arrange objects so that the doubles  all  come  together  if
there  are  lots of doubles and other things, so that you only need at most 1
pad.  I.e., you would want to store
    int * double * int * double
as
    int * int * double * double

For another, it can cost you a bit of space.   The  worst  case  is  probably
something  like  a  list of Real64.real objects, where the average of 4 bytes
wasted is going to be noticable.

Next is the GC slow down.

At any rate, the first thing to do, which should be trivial, is to just  make
sure that non-stack non-heap double variables are stored aligned.