It therefore seems as first glance that file i/o and/or reg exprs
in scsh are the bull-dogs, my guess is file i/o moreso than reg exprs.
I've spent the last two days working over the I/O system. The optional
argument parsing and defaulting machinery was not very efficient, which
really nailed you in I/O because the target port is always optional,
defaulting to (current-input-port) or (current-output-port). Improving
optional argument handling trimmed 1/3 of the time off of a loop to
read every line in /usr/dict/words.
We'll have the new optional-arg stuff in the next release.
Regexps are still a dog, since we don't precompile them.