Fix 2 performance issue in Style Configurator

Fix #14321

PowerEditor/src/WinControls/ColourPicker/WordStyleDlg.cpp

@@ -284,7 +284,7 @@ intptr_t CALLBACK WordStyleDlg::run_dlgProc(UINT Message, WPARAM wParam, LPARAM
 				{
 					updateExtension();
 					notifyDataModified();
-					apply();
+					// apply(); // apply() function has no effect on adding & modifying user defined extension, but it's just time consuming
 				}
 			}
 			else
@@ -872,7 +872,15 @@ void WordStyleDlg::setStyleListFromLexer(int index)
 		// then restore the status after sending this message.
 		bool isDirty = _isDirty;
 		bool isThemeDirty = _isThemeDirty;
-		::SendDlgItemMessage(_hSelf, IDC_USER_EXT_EDIT, WM_SETTEXT, 0, reinterpret_cast<LPARAM>(userExt));
+
+		constexpr int NB_MAX = 256;
+		TCHAR currentExt[NB_MAX]{};
+		::SendDlgItemMessage(_hSelf, IDC_USER_EXT_EDIT, WM_GETTEXT, NB_MAX, reinterpret_cast<LPARAM>(currentExt));
+
+		if (userExt && lstrcmp(currentExt, userExt) != 0)
+		{
+			::SendDlgItemMessage(_hSelf, IDC_USER_EXT_EDIT, WM_SETTEXT, 0, reinterpret_cast<LPARAM>(userExt));
+		}
 		_isDirty = isDirty;
 		_isThemeDirty = isThemeDirty;
 		::EnableWindow(::GetDlgItem(_hSelf, IDC_SAVECLOSE_BUTTON), isDirty || isThemeDirty);