Hi,

According to Alain (Frisch I guess), in the bug report that I pointed,
Array.blit causes checks for unboxed floats for every check, and also
has to update GC flags. I don't master the second point but he seems
to suggest that it can be optimized.

In the case of non-overlapping unboxed float arrays, I believe a
simple function similar to mine should work. But I'm not very
confident in mine yet.

Cheers.
-- 
David