performance comments

packages/web/src/datagrid/DataGrid.js

@@ -45,7 +45,13 @@ export default function DataGrid(props) {
               <ReferenceManager {...props} managerSize={managerSize} />
             </WidgetColumnBarItem>
           )}
-          <WidgetColumnBarItem title="Cell data" name="cellData" collapsed>
+          <WidgetColumnBarItem
+            title="Cell data"
+            name="cellData"
+            // cell data must be collapsed by default, because of performance reasons
+            // when not collapsed, onSelectionChanged of grid is set and RERENDER of this component is done on every selection change
+            collapsed
+          >
             {isFormView ? (
               <CellDataView selectedValue={formSelection} />
             ) : (

packages/web/src/datagrid/DataGridCore.js

@@ -1062,6 +1062,9 @@ export default function DataGridCore(props) {
           {_.range(firstVisibleRowScrollIndex, firstVisibleRowScrollIndex + visibleRowCountUpperBound).map(
             (rowIndex) => (
               <DataGridRow
+                // this component use React.memo
+                // when adding props, check, whether they are correctly memoized and row is not rerendered
+                // uncomment line console.log('RENDER ROW', rowIndex); in  DataGridRow.js for check
                 key={rowIndex}
                 grider={grider}
                 rowIndex={rowIndex}