Use String.Create.

Author: bgrainger

src/MySqlConnector/Core/ServerSession.cs

@@ -161,6 +161,34 @@ public async Task PrepareAsync(IMySqlCommand command, IOBehavior ioBehavior, Can
 				}
 
 				var parameterCount = cachedProcedure.Parameters.Count;
+#if NETCOREAPP2_1 || NETCOREAPP3_1 || NETSTANDARD2_1 || NET5_0
+				commandToPrepare = string.Create(commandText.Length + 7 + parameterCount * 2 + (parameterCount == 0 ? 1 : 0), (commandText, parameterCount), static (buffer, state) =>
+				{
+					buffer[0] = 'C';
+					buffer[1] = 'A';
+					buffer[2] = 'L';
+					buffer[3] = 'L';
+					buffer[4] = ' ';
+					buffer = buffer.Slice(5);
+					state.commandText.AsSpan().CopyTo(buffer);
+					buffer = buffer.Slice(state.commandText.Length);
+					buffer[0] = '(';
+					buffer = buffer.Slice(1);
+					if (state.parameterCount > 0)
+					{
+						buffer[0] = '?';
+						buffer = buffer.Slice(1);
+						for (var i = 1; i < state.parameterCount; i++)
+						{
+							buffer[0] = ',';
+							buffer[1] = '?';
+							buffer = buffer.Slice(2);
+						}
+					}
+					buffer[0] = ')';
+					buffer[1] = ';';
+				});
+#else
 				var callStatement = new StringBuilder("CALL ", commandText.Length + 8 + parameterCount * 2);
 				callStatement.Append(commandText);
 				callStatement.Append('(');
@@ -172,6 +200,7 @@ public async Task PrepareAsync(IMySqlCommand command, IOBehavior ioBehavior, Can
 					callStatement[callStatement.Length - 1] = ')';
 				callStatement.Append(';');
 				commandToPrepare = callStatement.ToString();
+#endif
 			}
 			else
 			{