patch 8.1.0372: screen updating slow when 'cursorline' is setv8.1.0372

Problem:    Screen updating slow when 'cursorline' is set.
Solution:   Only redraw the old and new cursor line, not all lines.

1 files changed, 20 insertions, 1 deletions

diff --git a/src/move.c b/src/move.c
index b2b84868a..68f8ae4a4 100644
--- a/src/move.c
+++ b/src/move.c
@@ -123,6 +123,10 @@ comp_botline(win_T *wp)
     set_empty_rows(wp, done);
 }
 
+#ifdef FEAT_SYN_HL
+static linenr_T	last_cursorline = 0;
+#endif
+
 /*
  * Redraw when w_cline_row changes and 'relativenumber' or 'cursorline' is
  * set.
@@ -140,7 +144,22 @@ redraw_for_cursorline(win_T *wp)
 	    && !pum_visible()
 # endif
 	    )
-	redraw_win_later(wp, SOME_VALID);
+    {
+#ifdef FEAT_SYN_HL
+	if (!wp->w_p_rnu && wp->w_redr_type <= VALID && last_cursorline != 0)
+	{
+	    // "last_cursorline" may be set for another window, worst case we
+	    // redraw too much.  This is optimized for moving the cursor around
+	    // in the same window.
+	    redrawWinline(wp, last_cursorline, FALSE);
+	    redrawWinline(wp, wp->w_cursor.lnum, FALSE);
+	    last_cursorline = wp->w_cursor.lnum;
+	    redraw_win_later(wp, VALID);
+	}
+	else
+#endif
+	    redraw_win_later(wp, SOME_VALID);
+    }
 }
 
 /*