GNU’s current value for this is 400k. I actually run with a value of about 60 megabytes most of the time; this change is only to 32 megabytes. APPROVE COMMIT NOTE: This patch has been committed # HG changeset patch # User Aidan Kehoe <kehoea(a)parhasard.net&gt; # Date 1489966027 0 # Sun Mar 19 23:27:07 2017 +0000 # Node ID 74b4d4c11264e149d03d748b9c34f253a69801bf # Parent 0ae4d70fef9389d2d99dc048cc86bb5745854680 Increase GC_CONS_THRESHOLD to better reflect current RAM sizes. src/ChangeLog addition: 2017-03-19 Aidan Kehoe <kehoea(a)parhasard.net&gt; * gc.c (GC_CONS_THRESHOLD): Increase this (from about 2 megabytes to about 32) and the related incremental-GC defaults, giving better performance with modern RAM sizes. diff -r 0ae4d70fef93 -r 74b4d4c11264 src/ChangeLog --- a/src/ChangeLog Thu Mar 16 00:40:32 2017 +0000 +++ b/src/ChangeLog Sun Mar 19 23:27:07 2017 +0000 ＠＠ -1,3 +1,10 ＠＠ +2017-03-19 Aidan Kehoe <kehoea(a)parhasard.net&gt; + + * gc.c (GC_CONS_THRESHOLD): + Increase this (from about 2 megabytes to about 32) and the related + incremental-GC defaults, giving better performance with modern RAM + sizes. + 2017-03-15 Aidan Kehoe <kehoea(a)parhasard.net&gt; * lread.c (read1): diff -r 0ae4d70fef93 -r 74b4d4c11264 src/gc.c --- a/src/gc.c Thu Mar 16 00:40:32 2017 +0000 +++ b/src/gc.c Sun Mar 19 23:27:07 2017 +0000 ＠＠ -361,14 +361,14 ＠＠ /* Number of bytes of consing since gc before a full gc should happen. */ -#define GC_CONS_THRESHOLD 2000000 - +#define GC_CONS_THRESHOLD 32000000 + /* Number of bytes of consing since gc before another cycle of the gc should happen in incremental mode. */ -#define GC_CONS_INCREMENTAL_THRESHOLD 200000 +#define GC_CONS_INCREMENTAL_THRESHOLD 800000 /* Number of elements marked in one cycle of incremental GC. */ -#define GC_INCREMENTAL_TRAVERSAL_THRESHOLD 100000 +#define GC_INCREMENTAL_TRAVERSAL_THRESHOLD 400000 /* Number of bytes of consing done since the last GC. */ EMACS_INT consing_since_gc; -- ‘As I sat looking up at the Guinness ad, I could never figure out / How your man stayed up on the surfboard after forty pints of stout’ (C. Moore)