[Emacs-diffs] emacs-25 0be6725 1/2: Document problem: slow screen refresh on missing font.

[Vincent Belaïche]

branch: emacs-25
commit 0be672542ad60e6c73d36b7fdc1b6786786595ad
Author: Vincent Belaïche <address@hidden>
Commit: Vincent Belaïche <address@hidden>

    Document problem: slow screen refresh on missing font.
    
    See discussion of bug#22519 for more on this.
---
 etc/PROBLEMS |   14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/etc/PROBLEMS b/etc/PROBLEMS
index 31f38e3..84d39a4 100644
--- a/etc/PROBLEMS
+++ b/etc/PROBLEMS
@@ -749,6 +749,20 @@ the following variables: tex-font-script-display (how much 
to
 lower/raise); tex-suscript-height-ratio (how much smaller than
 normal); tex-suscript-height-minimum (minimum height).
 
+** Screen refresh is slow when there are special characters for which no 
suitable font is available
+
+If the display is too slow in refreshing when you scroll to a new
+region, or when you edit the buffer, it might be due to the fact that
+some characters cannot be displayed in the default font, and Emacs is
+spending too much time in looking for a suitable font to display them.
+
+You can suspect this if you have several characters that are displayed
+as small rectangles containing a hexadecimal code inside.
+
+The solution is to install the appropriate fonts on your machine. For
+instance if you are editing a text with a lot of math symbols, then
+installing a font like 'Symbola' should solve this problem.
+
 * Internationalization problems
 
 ** M-{ does not work on a Spanish PC keyboard.