master cf4ccc58284: Speed up duplicate-line by a factor of 2

[Mattias Engdegård]

branch: master
commit cf4ccc58284de50959ea66b1cd2655ab2fa4d15b
Author: Mattias Engdegård <mattiase@acm.org>
Commit: Mattias Engdegård <mattiase@acm.org>

    Speed up duplicate-line by a factor of 2
    
    * lisp/misc.el (duplicate-line): Add the newline to the string to be
    inserted instead of inserting it separately.
    This makes duplicate-line as fast as duplicate-dwim with a contiguous
    region.  Both could easily be made faster yet by making the code more
    complex.
---
 lisp/misc.el | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/lisp/misc.el b/lisp/misc.el
index 81769696f95..de82b97fa6f 100644
--- a/lisp/misc.el
+++ b/lisp/misc.el
@@ -71,13 +71,15 @@ Also see the `copy-from-above-command' command."
   (interactive "p")
   (unless n
     (setq n 1))
-  (let ((line (buffer-substring (line-beginning-position) 
(line-end-position))))
+  (let ((line (concat (buffer-substring (line-beginning-position)
+                                        (line-end-position))
+                      "\n")))
     (save-excursion
       (forward-line 1)
       (unless (bolp)
         (insert "\n"))
       (dotimes (_ n)
-        (insert line "\n")))))
+        (insert line)))))
 
 (declare-function rectangle--duplicate-right "rect" (n))