From 36ec3d1fd3d0940e76f81482b9a834265155c5a3 Mon Sep 17 00:00:00 2001
From: Phil Scott <phil.scott@gmail.com>
Date: Sun, 4 Apr 2021 12:56:04 -0400
Subject: [PATCH] Adds rune width caching for cell length calculations

---
 src/Spectre.Console/Internal/Cell.cs | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/src/Spectre.Console/Internal/Cell.cs b/src/Spectre.Console/Internal/Cell.cs
index e30fe2a..3bdfd9d 100644
--- a/src/Spectre.Console/Internal/Cell.cs
+++ b/src/Spectre.Console/Internal/Cell.cs
@@ -4,11 +4,14 @@ namespace Spectre.Console
 {
     internal static class Cell
     {
+        private static readonly int?[] _runeWidthCache = new int?[char.MaxValue];
+
         public static int GetCellLength(string text)
         {
             var sum = 0;
-            foreach (var rune in text)
+            for (var index = 0; index < text.Length; index++)
             {
+                var rune = text[index];
                 sum += GetCellLength(rune);
             }
 
@@ -28,7 +31,7 @@ namespace Spectre.Console
                 return 1;
             }
 
-            return UnicodeCalculator.GetWidth(rune);
+            return _runeWidthCache[rune] ??= UnicodeCalculator.GetWidth(rune);
         }
     }
 }