Avoid slow startup in daemon mode when global-linum-mode is on

* lisp/linum.el (linum-on): Don't turn on linum-mode in a
non-client frame of a daemon session.  (Bug#27210)

1 files changed, 10 insertions, 1 deletions

diff --git a/lisp/linum.el b/lisp/linum.el
index 8baa263f0b3..9cfb94dab68 100644
--- a/lisp/linum.el
+++ b/lisp/linum.el
@@ -112,7 +112,16 @@ Linum mode is a buffer-local minor mode."
 (define-globalized-minor-mode global-linum-mode linum-mode linum-on)
 
 (defun linum-on ()
-  (unless (minibufferp)
+  (unless (or (minibufferp)
+              ;; Turning linum-mode in the daemon's initial frame
+              ;; could significantly slow down startup, if the buffer
+              ;; in which this is done is large, because Emacs thinks
+              ;; the "window" spans the entire buffer then.  This
+              ;; could happen when restoring session via desktop.el,
+              ;; if some large buffer was under linum-mode when
+              ;; desktop was saved.  So we disable linum-mode for
+              ;; non-client frames in a daemon session.
+              (and (daemonp) (null (frame-parameter nil 'client))))
     (linum-mode 1)))
 
 (defun linum-delete-overlays ()