RE: [External] : Re: Shrinking the C core

[Drew Adams]

> > The discussion about floor started from Alfred using `floor'
> > as an example where CL uses system-dependent optimizations
> > and thus being much faster.
> 
> So the answer to the question, Why is SBCL faster?
> is "optimizations". And the answer to the question, Why don't
> we have those optimizations? is "they are not portable"?

https://www.cs.cmu.edu/Groups/AI/html/cltl/clm/node103.html#SECTION001300000000000000000

Common Lisp is a standard.  Different implementations
of it should respect the standard, but the standard
allows for different behaviors to some extent, esp.
wrt performance.  CL has multiple ways of declaring
different levels of optimization, which a given
implementation can support or not.

Particular optimizations are not expected to be
portable.