[Emacs-diffs] emacs-25 e992ac0: Fix sluggish display of symbols in UTF-8 language environment

[Eli Zaretskii]

branch: emacs-25
commit e992ac0a639d01df8f04c18061b0d73f792ff2c2
Author: Eli Zaretskii <address@hidden>
Commit: Eli Zaretskii <address@hidden>

    Fix sluggish display of symbols in UTF-8 language environment
    
    * lisp/international/fontset.el (setup-default-fontset): Make sure
    Symbola and FreeMono are set up in the default fontset as belonging
    to the "iso10646-1" registry.  In the UTF-8 locale, this avoids a
    long and futile search for a suitable font, whose side effect is a
    lot of consing, which then hits the font-cache compacting issue,
    and causes very sluggish redisplay of characters displayed by
    these fonts.  All this happens because the default for the
    registry is "iso8859-1".  (Bug#24953)
---
 lisp/international/fontset.el |    5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/lisp/international/fontset.el b/lisp/international/fontset.el
index 612c0a0..659f03a 100644
--- a/lisp/international/fontset.el
+++ b/lisp/international/fontset.el
@@ -812,10 +812,11 @@
              (#x1F700 . #x1F77F)       ;; Alchemical Symbols
              (#x1F780 . #x1F7FF)       ;; Geometric Shapes Extended
              (#x1F800 . #x1F8FF)))     ;; Supplemental Arrows-C
-    (set-fontset-font "fontset-default" symbol-subgroup "Symbola" nil 
'prepend))
+    (set-fontset-font "fontset-default" symbol-subgroup
+                      '("Symbola" . "iso10646-1") nil 'prepend))
   ;; Box Drawing and Block Elements
   (set-fontset-font "fontset-default" '(#x2500 . #x259F)
-                    "FreeMono" nil 'prepend)
+                    '("FreeMono" . "iso10646-1") nil 'prepend)
 
   ;; Since standard-fontset-spec on X uses fixed-medium font, which
   ;; gets mapped to a iso8859-1 variant, we would like to prefer its