From a0e1cfc0683ed768a5d84e31562aeebf2e30acef Mon Sep 17 00:00:00 2001
From: James Garbutt <43081j@users.noreply.github.com>
Date: Mon, 20 Jul 2026 15:37:29 +0100
Subject: [PATCH 1/2] perf: pre-compute instance init functions

When we construct a row, we iterate over the table's features and
initialise any which have an `initRowInstanceData`.

This is expensive since most don't have such a method.

We actually know when we construct the table which features have this
method. This changes the table construction to store the initialisers up
front so when we create a row, we can just iterate the already known
initialisers.
---
 packages/table-core/src/core/rows/constructRow.ts      |  6 +++---
 packages/table-core/src/core/table/constructTable.ts   | 10 ++++++++++
 .../src/core/table/coreTablesFeature.types.ts          |  5 +++++
 3 files changed, 18 insertions(+), 3 deletions(-)

diff --git a/packages/table-core/src/core/rows/constructRow.ts b/packages/table-core/src/core/rows/constructRow.ts
index 663f346962..a950f00505 100644
--- a/packages/table-core/src/core/rows/constructRow.ts
+++ b/packages/table-core/src/core/rows/constructRow.ts
@@ -59,9 +59,9 @@ export const constructRow = <
   row.subRows = subRows ?? []
 
   // Initialize instance-specific data (e.g., caches) for features that need it
-  const features = Object.values(table._features)
-  for (let i = 0; i < features.length; i++) {
-    features[i]!.initRowInstanceData?.(row)
+  const initFns = table._rowInstanceInitFns!
+  for (let i = 0; i < initFns.length; i++) {
+    initFns[i]!(row as Row<TFeatures, TData>)
   }
 
   return row as Row<TFeatures, TData>
diff --git a/packages/table-core/src/core/table/constructTable.ts b/packages/table-core/src/core/table/constructTable.ts
index 3a2f648966..520a33303a 100644
--- a/packages/table-core/src/core/table/constructTable.ts
+++ b/packages/table-core/src/core/table/constructTable.ts
@@ -68,6 +68,16 @@ export function constructTable<
 
   const featuresList: Array<TableFeature> = Object.values(table._features)
 
+  const rowInstanceInitFns: Array<
+    NonNullable<TableFeature['initRowInstanceData']>
+  > = []
+  for (const feature of featuresList) {
+    if (feature.initRowInstanceData) {
+      rowInstanceInitFns.push(feature.initRowInstanceData)
+    }
+  }
+  table._rowInstanceInitFns = rowInstanceInitFns
+
   const defaultOptions = featuresList.reduce((obj, feature) => {
     return Object.assign(obj, feature.getDefaultTableOptions?.(table))
   }, {}) as TableOptions<TFeatures, TData>
diff --git a/packages/table-core/src/core/table/coreTablesFeature.types.ts b/packages/table-core/src/core/table/coreTablesFeature.types.ts
index 8570660430..80afe099e7 100644
--- a/packages/table-core/src/core/table/coreTablesFeature.types.ts
+++ b/packages/table-core/src/core/table/coreTablesFeature.types.ts
@@ -5,6 +5,7 @@ import type { RowModelFns } from '../../types/RowModelFns'
 import type { RowData, Updater } from '../../types/type-utils'
 import type {
   IsAny,
+  TableFeature,
   TableFeatures,
   ValidateFeatureSlots,
 } from '../../types/TableFeatures'
@@ -188,6 +189,10 @@ export interface Table_CoreProperties<
    * Prototype cache for Row objects - shared by all rows in this table
    */
   _rowPrototype?: object
+  /**
+   * Cache of the `initRowInstanceData` functions for features that define one.
+   */
+  _rowInstanceInitFns?: Array<NonNullable<TableFeature['initRowInstanceData']>>
   /**
    * The readonly derived atoms for each `TableState` slice. Each derives from
    * its corresponding `baseAtom` plus, optionally, a per-slice external atom or

From a0057d30a2c1f0a07c4a7bafe160c07276cc9c30 Mon Sep 17 00:00:00 2001
From: James Garbutt <43081j@users.noreply.github.com>
Date: Mon, 20 Jul 2026 16:10:40 +0100
Subject: [PATCH 2/2] fix(table-core): bind initialiser to feature

Co-authored-by: coderabbitai[bot] <136622811+coderabbitai[bot]@users.noreply.github.com>
---
 packages/table-core/src/core/table/constructTable.ts | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/packages/table-core/src/core/table/constructTable.ts b/packages/table-core/src/core/table/constructTable.ts
index 520a33303a..2d706c8234 100644
--- a/packages/table-core/src/core/table/constructTable.ts
+++ b/packages/table-core/src/core/table/constructTable.ts
@@ -73,7 +73,7 @@ export function constructTable<
   > = []
   for (const feature of featuresList) {
     if (feature.initRowInstanceData) {
-      rowInstanceInitFns.push(feature.initRowInstanceData)
+      rowInstanceInitFns.push(feature.initRowInstanceData.bind(feature))
     }
   }
   table._rowInstanceInitFns = rowInstanceInitFns