More Improvement to unix timestamp performance

src/NzbDrone.Common/Extensions/StringExtensions.cs

@@ -257,5 +257,18 @@ namespace NzbDrone.Common.Extensions
         {
             return input.Contains(':') ? $"[{input}]" : input;
         }
+
+        public static bool IsAllDigits(this string input)
+        {
+            foreach (var c in input)
+            {
+                if (c < '0' || c > '9')
+                {
+                    return false;
+                }
+            }
+
+            return true;
+        }
     }
 }

src/NzbDrone.Core/Parser/DateTimeUtil.cs

@@ -2,6 +2,7 @@ using System;
 using System.Globalization;
 using System.Linq;
 using System.Text.RegularExpressions;
+using NzbDrone.Common.Extensions;
 
 namespace NzbDrone.Core.Parser
 {
@@ -123,7 +124,7 @@ namespace NzbDrone.Core.Parser
                 str = str.Trim();
 
                 // try parsing the str as an unix timestamp
-                if (str.All(char.IsDigit) && long.TryParse(str, out var unixTimeStamp))
+                if (str.IsAllDigits() && long.TryParse(str, out var unixTimeStamp))
                 {
                     return UnixTimestampToDateTime(unixTimeStamp);
                 }