Despite that this optimisation can’t really be added to distinguish between SXEmacs and XEmacs, I still think it’s worthwhile. Here is X for the top fifteen most frequent calls to (featurep 'X) in the packages tree: 250 xemacs 58 mule 42 xpm 32 menubar 27 toolbar 19 custom 15 infodock 12 sparcworks 10 ediff-init 10 itimer 10 skk-cursor 10 x 8 ange-ftp 8 font-lock There are in total 860 such calls (that is, simple (featreup 'X) calls), so eliminating (featurep 'xemacs) is disproportionately helpful. The other features in my patch, not so much, but they do provide a framework should we ever take the time to work out which features have always been available ever since the last time our bytecode became incompatible. 2007-10-01 Aidan Kehoe <kehoea(a)parhasard.net&gt; * byte-optimize.el: * byte-optimize.el (byte-optimize-ever-present-features): New. * byte-optimize.el (byte-optimize-featurep): New. Optimise calls to (featurep 'xemacs) to t, since our byte code refuses to run on GNU Emacs. Also optimises away checks for cl, cl-extra, cl-19 and backquote, a conservative list of those features that have been available in every XEmacs build since the last time our opcodes changed. XEmacs Trunk source patch: Diff command: cvs -q diff -u Files affected: lisp/byte-optimize.el =================================================================== RCS Index: lisp/byte-optimize.el =================================================================== RCS file: /pack/xemacscvs/XEmacs/xemacs/lisp/byte-optimize.el,v retrieving revision 1.12 diff -u -r1.12 byte-optimize.el --- lisp/byte-optimize.el 2007/09/15 19:11:55 1.12 +++ lisp/byte-optimize.el 2007/10/01 15:21:25 ＠＠ -1169,6 +1169,21 ＠＠ (eval form) form))) +(defvar byte-optimize-ever-present-features + '(xemacs cl cl-extra cl-19 backquote)) + +(put 'featurep 'byte-optimizer 'byte-optimize-featurep) +(defun byte-optimize-featurep (form) + (let ((to-check (cdr-safe form))) + (if (memq (car-safe + (cdr-safe + (car-safe + (cdr-safe + form)))) + byte-optimize-ever-present-features) + t + form))) +  ;;; enumerating those functions which need not be called if the returned ;;; value is not used. That is, something like -- On the quay of the little Black Sea port, where the rescued pair came once more into contact with civilization, Dobrinton was bitten by a dog which was assumed to be mad, though it may only have been indiscriminating. (Saki) _______________________________________________ XEmacs-Patches mailing list XEmacs-Patches(a)xemacs.org http://calypso.tux.org/cgi-bin/mailman/listinfo/xemacs-patches