[xpm maint] Add some perf ideas to HACKING; nfc.

diff --git a/packages/xpm/HACKING b/packages/xpm/HACKING
index c72f20616cb969e7b2182583d7da5ae76f2c484d..ff04c62820ebd34b615942494cc519c9a1d0873d 100644 (file)
--- a/packages/xpm/HACKING
+++ b/packages/xpm/HACKING
@@ -24,6 +24,9 @@ This file is both a guide for newcomers and a todo list for oldstayers.
 ***** import from rectangle
 ******* as-is (dangerous)
 ******* w/ char-to-px quantization
+*** perf
+***** ??? use ‘binary’ coding system
+***** make ‘xpm-raster’ do [vh]-line expansion
 * etc
 #+odd