From d77e1c1ffcda2309507a8f8e137a77f8d464d08b Mon Sep 17 00:00:00 2001
From: Earle Castledine <earlec@21csw.com>
Date: Fri, 19 May 2023 11:47:51 +0800
Subject: [PATCH] perf(DataTable): speed up select-all with large tables

Rewrite `setAllSelectedState` to improve peformance with
large tables. In my test case with 10000 rows, selecting
all rows previously took 14000ms. This fix reduces it to
8ms. It uses one instance of (local) variable mutation.
Fixes #6146.

.
---
 .../src/components/DataTable/DataTable.js     | 21 ++++++++-----------
 1 file changed, 9 insertions(+), 12 deletions(-)

diff --git a/packages/react/src/components/DataTable/DataTable.js b/packages/react/src/components/DataTable/DataTable.js
index 0c43aa03f232..803f8011295b 100644
--- a/packages/react/src/components/DataTable/DataTable.js
+++ b/packages/react/src/components/DataTable/DataTable.js
@@ -486,19 +486,16 @@ class DataTable extends React.Component {
    */
   setAllSelectedState = (initialState, isSelected, filteredRowIds) => {
     const { rowIds } = initialState;
+    const isFiltered = rowIds.length != filteredRowIds.length;
     return {
-      rowsById: rowIds.reduce(
-        (acc, id) => ({
-          ...acc,
-          [id]: {
-            ...initialState.rowsById[id],
-            ...(!initialState.rowsById[id].disabled && {
-              isSelected: filteredRowIds.includes(id) && isSelected,
-            }),
-          },
-        }),
-        {}
-      ),
+      rowsById: rowIds.reduce((acc, id) => {
+        const row = { ...initialState.rowsById[id] };
+        if (!row.disabled && (!isFiltered || filteredRowIds.includes(id))) {
+          row.isSelected = isSelected;
+        }
+        acc[id] = row; // Local mutation for performance with large tables
+        return acc;
+      }, {}),
     };
   };