patch 8.1.0822: peeking and flushing output slows down execution commit https://github.com/vim/vim/commit/cb574f415486adff645ce384979bfecf27f5be8c Author: Bram Moolenaar <Bram@vim.org> Date: Fri Jan 25 22:29:57 2019 +0100 patch 8.1.0822: peeking and flushing output slows down execution Problem: Peeking and flushing output slows down execution. Solution: Do not update the mode message when global_busy is set. Do not flush when only peeking for a character. (Ken Takata)

--- a/src/getchar.c
+++ b/src/getchar.c
@@ -3039,9 +3039,10 @@ inchar(
 
 	/*
 	 * Always flush the output characters when getting input characters
-	 * from the user.
+	 * from the user and not just peeking.
 	 */
-	out_flush();
+	if (wait_time == -1L || wait_time > 10L)
+	    out_flush();
 
 	/*
 	 * Fill up to a third of the buffer, because each character may be