commit 44ec60d to speed up MAPPLY1 via lambda optimization

Hey, I just saw commit 44ec60d which avoids calling COERCE on Lisp
lambda expressions, which makes a lot of stuff faster, and makes
pattern-matching stuff (e.g. ezunits) much, much faster. That is
really terrific!

It has always bothered me that pattern-matching stuff is (or was, I
guess) much slower than built-in simplification, to the extent that it
makes me think twice about bringing pattern matching into the picture
for the purely practical reason that it slows down everything
noticeably, so this optimization is going to be really helpful.

David, may I ask how you discovered the COERCE bottleneck in MAPPLY1 ?

Thanks a lot,

Robert