From 0c4d885d5b2590e6db37d5ed81ef7df4df23c028 Mon Sep 17 00:00:00 2001
From: AnHardt <github@kitelab.de>
Date: Thu, 19 May 2016 15:41:09 +0200
Subject: [PATCH] Speedup sreen update delay

Speedup sreen update delay
and correct a comment.

A module division by 10 is slooooow. (powers of 2 are fast - but then you can AND a bitmask with the same result)
---
 Marlin/ultralcd.cpp | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/Marlin/ultralcd.cpp b/Marlin/ultralcd.cpp
index 7f0b9a271..4d7f80b95 100644
--- a/Marlin/ultralcd.cpp
+++ b/Marlin/ultralcd.cpp
@@ -282,7 +282,6 @@ menuPosition menu_history[10];
 uint8_t menu_history_depth = 0;
 
 millis_t next_lcd_update_ms;
-uint8_t lcd_status_update_delay;
 bool ignore_click = false;
 bool wait_for_unclick;
 bool defer_return_to_status = false;
@@ -2248,9 +2247,13 @@ void lcd_update() {
       }
     #endif //ULTIPANEL
 
-    // Simply redraw the Info Screen 10 times a second
-    if (currentMenu == lcd_status_screen && !(++lcd_status_update_delay % 10))
+    // Here we arrive every ~100ms when ideling often enough.
+    // Instead of tracking the changes simply redraw the Info Screen ~1 time a second.
+    static int8_t lcd_status_update_delay = 1; // first update one loop delayed
+    if (currentMenu == lcd_status_screen && !lcd_status_update_delay--) {
+      lcd_status_update_delay = 9;
       lcdDrawUpdate = LCDVIEW_REDRAW_NOW;
+    }
 
     if (lcdDrawUpdate) {