Some trivial optimizations.

layout.c

@@ -405,7 +405,8 @@ layout_fix_panes(struct window *w, struct window_pane *skip)
 	struct window_pane	*wp;
 	struct layout_cell	*lc;
 	int			 status, scrollbars, sb_pos, sb_w, sb_pad;
-	u_int			 sx, sy;
+	int			 old_xoff, old_yoff, changed = 0;
+	u_int			 sx, sy, old_sx, old_sy;
 
 	status = window_get_pane_status(w);
 	scrollbars = options_get_number(w->options, "pane-scrollbars");
@@ -415,6 +416,11 @@ layout_fix_panes(struct window *w, struct window_pane *skip)
 		if ((lc = wp->layout_cell) == NULL || wp == skip)
 			continue;
 
+		old_xoff = wp->xoff;
+		old_yoff = wp->yoff;
+		old_sx = wp->sx;
+		old_sy = wp->sy;
+
 		wp->xoff = lc->xoff;
 		wp->yoff = lc->yoff;
 		sx = lc->sx;
@@ -452,8 +458,15 @@ layout_fix_panes(struct window *w, struct window_pane *skip)
 		}
 
 		window_pane_resize(wp, sx, sy);
+
+		if (wp->xoff != old_xoff ||
+		    wp->yoff != old_yoff ||
+		    wp->sx != old_sx ||
+		    wp->sy != old_sy)
+			changed = 1;
 	}
-	screen_redraw_invalidate_scene(w);
+	if (changed)
+		screen_redraw_invalidate_scene(w);
 }
 
 /* Count the number of available cells in a layout. */
@@ -774,10 +787,15 @@ layout_resize_floating_pane_to(struct window_pane *wp, enum layout_type type,
 		return;
 	}
 
-	if (type == LAYOUT_TOPBOTTOM)
+	if (type == LAYOUT_TOPBOTTOM) {
+		if (lc->sy == size)
+			return;
 		lc->sy = size;
-	else
+	} else {
+		if (lc->sx == size)
+			return;
 		lc->sx = size;
+	}
 	screen_redraw_invalidate_scene(wp->window);
 }
 
@@ -793,6 +811,8 @@ layout_resize_floating_pane(struct window_pane *wp, enum layout_type type,
 		*cause = xstrdup("pane is not floating");
 		return;
 	}
+	if (change == 0)
+		return;
 
 	if (type == LAYOUT_TOPBOTTOM) {
 		size = lc->sy + change;

screen-redraw.c

@@ -164,6 +164,9 @@ struct redraw_build_cell {
 	struct redraw_span_data	 data;
 };
 
+static struct redraw_build_cell	*screen_redraw_cells;
+static size_t			 screen_redraw_ncells;
+
 /* Context for building the scene. */
 struct redraw_build_ctx {
 	struct client				*c;
@@ -864,22 +867,24 @@ screen_redraw_make_scene(struct client *c)
 	if (bctx.sx != 0 && bctx.sy > SIZE_MAX / bctx.sx)
 		fatalx("%s: too many cells", __func__);
 	ncells = (size_t)bctx.sx * bctx.sy;
-	if (ncells > SIZE_MAX / sizeof *bctx.cells)
-		fatalx("%s: too many cells", __func__);
-	bctx.cells = xmalloc(ncells * sizeof *bctx.cells);
+	if (ncells > screen_redraw_ncells) {
+		screen_redraw_cells = xreallocarray(screen_redraw_cells, ncells,
+		    sizeof *screen_redraw_cells);
+		screen_redraw_ncells = ncells;
+	}
+	bctx.cells = screen_redraw_cells;
 	for (y = 0; y < bctx.sy; y++) {
 		for (x = 0; x < bctx.sx; x++)
 			screen_redraw_reset_cell(&bctx, x, y);
 	}
 
 	TAILQ_FOREACH_REVERSE(wp, &bctx.w->z_index, window_panes_zindex, zentry)
-	    screen_redraw_mark_pane(&bctx, wp);
+		screen_redraw_mark_pane(&bctx, wp);
 
 	screen_redraw_mark_two_pane_colours(&bctx);
 	screen_redraw_finish_scene(&bctx, scene);
 	log_debug("%s: finished @%u scene build", c->name, scene->w->id);
 
-	free(bctx.cells);
 	return (scene);
 }
 
@@ -1463,8 +1468,10 @@ screen_redraw_draw(struct client *c, struct window_pane *wp, int flags)
 		}
 	}
 
-	log_debug("%s: starting @%u redraw (%s)", c->name, w->id,
-	    screen_redraw_flags_string(flags));
+	if (log_get_level() != 0) {
+		log_debug("%s: starting @%u redraw (%s)", c->name, w->id,
+		    screen_redraw_flags_string(flags));
+	}
 
 	scene = screen_redraw_get_scene(c);
 	if (scene == NULL)