1 files changed, 5 insertions, 3 deletions

diff --git a/src/alloc.c b/src/alloc.c
index 28ca7804ee9..abb98a9eb68 100644
--- a/src/alloc.c
+++ b/src/alloc.c
@@ -641,9 +641,11 @@ buffer_memory_full (ptrdiff_t nbytes)
    implement Lisp objects; since pseudovectors can contain any C type,
    this is max_align_t.  On recent GNU/Linux x86 and x86-64 this can
    often waste up to 8 bytes, since alignof (max_align_t) is 16 but
-   typical vectors need only an alignment of 8.  However, it is not
-   worth the hassle to avoid this waste.  */
-enum { LISP_ALIGNMENT = alignof (union { max_align_t x; GCALIGNED_UNION }) };
+   typical vectors need only an alignment of 8.  Although shrinking
+   the alignment to 8 would save memory, it cost a 20% hit to Emacs
+   CPU performance on Fedora 28 x86-64 when compiled with gcc -m32.  */
+enum { LISP_ALIGNMENT = alignof (union { max_align_t x;
+                                         GCALIGNED_UNION_MEMBER }) };
 verify (LISP_ALIGNMENT % GCALIGNMENT == 0);
 
 /* True if malloc (N) is known to return storage suitably aligned for