commit https://github.com/vim/vim/commit/8240433f48f7383c281ba2453cc55f10b8ec47d9 Author: Bram Moolenaar <Bram@vim.org> Date: Sun Jul 10 17:00:38 2016 +0200 patch 7.4.2017 Problem: When there are many errors adding them to the quickfix list takes a long time. Solution: Add BLN_NOOPT. Don't call buf_valid() in buf_copy_options(). Remember the last file name used. When going through the buffer list start from the end of the list. Only call buf_valid() when autocommands were executed.

--- a/src/vim.h
+++ b/src/vim.h
@@ -941,6 +941,7 @@ extern char *(*dyn_libintl_textdomain)(c
 #define BLN_LISTED	2	/* put new buffer in buffer list */
 #define BLN_DUMMY	4	/* allocating dummy buffer */
 #define BLN_NEW		8	/* create a new buffer */
+#define BLN_NOOPT	16	/* don't copy options to existing buffer */
 
 /* Values for in_cinkeys() */
 #define KEY_OPEN_FORW	0x101