I was getting underruns in real time where I did not before,
and so I thought that it might be because I had been trying
out the doubles version of csound, which certainly must strain
the processor a bit more.  I went to my Csound5 directory,
and simply ran scons the same as before, but without specifying
doubles.  The executable that I got, does inform me that I am
using float samples now, but the when I ran the 'install.py'
script, it still warned me to set the OPCODEDIR64 environment
variable to /usr/local/lib/csound/plugins64.  I had a hunch
that if I had built the tree clean, the install script would
have known that I was not using doubles.  As a precaution,
I set OPCODEDIR to point to the plain plugins dir.  

Would someone care to elaborate as to the reason for the two directories,
and to the proper env settings, etc.  Also, do some people keep
two csound binaries around?  I was also curious as to why this
could not have been a command line option, rather than a recompile.

Thanks, as always the list is most responsive and helpful.

Toby