FindByName(ReadOnlySpan<char> name) for .Net9 + small optimization.

Author: kirsan31

src/System.Windows.Forms.DataVisualization/General/BaseCollections.cs

@@ -491,6 +491,23 @@ public virtual T FindByName(string name)
             return null;
         }
 
+#if NET9_0_OR_GREATER
+        /// <summary>
+        /// Finds the chart element by the name.<br/>
+        /// This method approaches an O(1) operation.
+        /// </summary>
+        /// <param name="name">The name.</param>
+        /// <returns></returns>
+        public virtual T FindByName(ReadOnlySpan<char> name)
+        {
+            int idx = IndexOf(name);
+            if (idx > -1)
+                return this[idx];
+
+            return null;
+        }
+#endif
+
         /// <summary>
         /// Inserts the specified item in the collection at the specified index.
         /// </summary>

src/System.Windows.Forms.DataVisualization/Utilities/XmlSerializer.cs

@@ -1028,19 +1028,14 @@ internal TypeConverter FindConverterByType(TypeConverterAttribute attr)
         // throws SecurityException or MethodAccessException when the converter class is internal.
         // Thats why we have this giant if - elseif here - to create type converters without reflection.
         if (_converterDict.Contains(attr.ConverterTypeName))
-        {
             return (TypeConverter)_converterDict[attr.ConverterTypeName];
-        }
-
-        string typeStr = attr.ConverterTypeName;
 
-        if (attr.ConverterTypeName.Contains(','))
-        {
-            typeStr = attr.ConverterTypeName.Split(',')[0];
-        }
+        ReadOnlySpan<char> typeStr = attr.ConverterTypeName.AsSpan();
+        int ind;
+        if ((ind = typeStr.IndexOf(',')) > -1)
+            typeStr = typeStr[..ind];
 
         TypeConverter result = null;
-
         if (typeStr.EndsWith(".CustomPropertiesTypeConverter", StringComparison.OrdinalIgnoreCase)) { result = new CustomPropertiesTypeConverter(); }
         else if (typeStr.EndsWith(".DoubleNanValueConverter", StringComparison.OrdinalIgnoreCase)) { result = new DoubleNanValueConverter(); }
         else if (typeStr.EndsWith(".DoubleDateNanValueConverter", StringComparison.OrdinalIgnoreCase)) { result = new DoubleDateNanValueConverter(); }
@@ -1072,7 +1067,8 @@ internal TypeConverter FindConverterByType(TypeConverterAttribute attr)
         else if (typeStr.EndsWith(".AnchorPointValueConverter", StringComparison.OrdinalIgnoreCase)) { result = new AnchorPointValueConverter(); }
         else if (typeStr.EndsWith(".AnnotationAxisValueConverter", StringComparison.OrdinalIgnoreCase)) { result = new AnnotationAxisValueConverter(); }
 
-        if (result != null) _converterDict[attr.ConverterTypeName] = result;
+        if (result is not null)
+            _converterDict[attr.ConverterTypeName] = result;
 
         return result;
     }