diff --git a/packages/x-data-grid-premium/src/hooks/features/aggregation/createAggregationLookup.ts b/packages/x-data-grid-premium/src/hooks/features/aggregation/createAggregationLookup.ts
index 0e91f89ecee6a..4294bf38db5ca 100644
--- a/packages/x-data-grid-premium/src/hooks/features/aggregation/createAggregationLookup.ts
+++ b/packages/x-data-grid-premium/src/hooks/features/aggregation/createAggregationLookup.ts
@@ -19,23 +19,20 @@ import {
 import { getAggregationRules } from './gridAggregationUtils';
 import { gridAggregationModelSelector } from './gridAggregationSelectors';
 
-const getAggregationCellValue = ({
-  apiRef,
-  groupId,
-  field,
-  aggregationFunction,
-  aggregationRowsScope,
-}: {
-  apiRef: React.MutableRefObject<GridApiPremium>;
-  groupId: GridRowId;
-  field: string;
-  aggregationFunction: GridAggregationFunction;
-  aggregationRowsScope: DataGridPremiumProcessedProps['aggregationRowsScope'];
-}) => {
+const getGroupAggregatedValue = (
+  groupId: GridRowId,
+  apiRef: React.MutableRefObject<GridApiPremium>,
+  aggregationRowsScope: DataGridPremiumProcessedProps['aggregationRowsScope'],
+  aggregatedFields: string[],
+  aggregationRules: GridAggregationRules,
+  position: GridAggregationPosition,
+) => {
+  const groupAggregationLookup: GridAggregationLookup[GridRowId] = {};
+  const aggregatedValues: { aggregatedField: string; values: any[] }[] = [];
+
+  const rowIds = apiRef.current.getRowGroupChildren({ groupId });
   const filteredRowsLookup = gridFilteredRowsLookupSelector(apiRef);
-  const rowIds: GridRowId[] = apiRef.current.getRowGroupChildren({ groupId });
 
-  const values: any[] = [];
   rowIds.forEach((rowId) => {
     if (aggregationRowsScope === 'filtered' && filteredRowsLookup[rowId] === false) {
       return;
@@ -53,51 +50,43 @@ const getAggregationCellValue = ({
       return;
     }
 
-    if (typeof aggregationFunction.getCellValue === 'function') {
-      const row = apiRef.current.getRow(rowId);
-      values.push(aggregationFunction.getCellValue({ row }));
-    } else {
-      values.push(apiRef.current.getCellValue(rowId, field));
-    }
-  });
+    const row = apiRef.current.getRow(rowId);
 
-  return aggregationFunction.apply({
-    values,
-    groupId,
-    field, // Added per user request in https://github.com/mui/mui-x/issues/6995#issuecomment-1327423455
-  });
-};
+    for (let j = 0; j < aggregatedFields.length; j += 1) {
+      const aggregatedField = aggregatedFields[j];
+      const columnAggregationRules = aggregationRules[aggregatedField];
 
-const getGroupAggregatedValue = ({
-  groupId,
-  apiRef,
-  aggregationRowsScope,
-  aggregatedFields,
-  aggregationRules,
-  position,
-}: {
-  groupId: GridRowId;
-  apiRef: React.MutableRefObject<GridApiPremium>;
-  aggregationRowsScope: DataGridPremiumProcessedProps['aggregationRowsScope'];
-  aggregatedFields: string[];
-  aggregationRules: GridAggregationRules;
-  position: GridAggregationPosition;
-}) => {
-  const groupAggregationLookup: GridAggregationLookup[GridRowId] = {};
+      const aggregationFunction = columnAggregationRules.aggregationFunction;
+      const field = aggregatedField;
 
-  for (let j = 0; j < aggregatedFields.length; j += 1) {
-    const aggregatedField = aggregatedFields[j];
-    const columnAggregationRules = aggregationRules[aggregatedField];
+      if (aggregatedValues[j] === undefined) {
+        aggregatedValues[j] = {
+          aggregatedField,
+          values: [],
+        };
+      }
+
+      if (typeof aggregationFunction.getCellValue === 'function') {
+        aggregatedValues[j].values.push(aggregationFunction.getCellValue({ row }));
+      } else {
+        const colDef = apiRef.current.getColumn(field);
+        aggregatedValues[j].values.push(apiRef.current.getRowValue(row, colDef));
+      }
+    }
+  });
+
+  for (let i = 0; i < aggregatedValues.length; i += 1) {
+    const { aggregatedField, values } = aggregatedValues[i];
+    const aggregationFunction = aggregationRules[aggregatedField].aggregationFunction;
+    const value = aggregationFunction.apply({
+      values,
+      groupId,
+      field: aggregatedField, // Added per user request in https://github.com/mui/mui-x/issues/6995#issuecomment-1327423455
+    });
 
     groupAggregationLookup[aggregatedField] = {
       position,
-      value: getAggregationCellValue({
-        apiRef,
-        groupId,
-        field: aggregatedField,
-        aggregationFunction: columnAggregationRules.aggregationFunction,
-        aggregationRowsScope,
-      }),
+      value,
     };
   }
 
@@ -115,11 +104,11 @@ export const createAggregationLookup = ({
   aggregationRowsScope: DataGridPremiumProcessedProps['aggregationRowsScope'];
   getAggregationPosition: DataGridPremiumProcessedProps['getAggregationPosition'];
 }): GridAggregationLookup => {
-  const aggregationRules = getAggregationRules({
-    columnsLookup: gridColumnLookupSelector(apiRef),
-    aggregationModel: gridAggregationModelSelector(apiRef),
+  const aggregationRules = getAggregationRules(
+    gridColumnLookupSelector(apiRef),
+    gridAggregationModelSelector(apiRef),
     aggregationFunctions,
-  });
+  );
 
   const aggregatedFields = Object.keys(aggregationRules);
   if (aggregatedFields.length === 0) {
@@ -143,14 +132,14 @@ export const createAggregationLookup = ({
     if (hasAggregableChildren) {
       const position = getAggregationPosition(groupNode);
       if (position != null) {
-        aggregationLookup[groupNode.id] = getGroupAggregatedValue({
-          groupId: groupNode.id,
+        aggregationLookup[groupNode.id] = getGroupAggregatedValue(
+          groupNode.id,
           apiRef,
-          aggregatedFields,
           aggregationRowsScope,
+          aggregatedFields,
           aggregationRules,
           position,
-        });
+        );
       }
     }
   };
diff --git a/packages/x-data-grid-premium/src/hooks/features/aggregation/gridAggregationUtils.ts b/packages/x-data-grid-premium/src/hooks/features/aggregation/gridAggregationUtils.ts
index 0f15aa74136b4..c84aae5d5e30b 100644
--- a/packages/x-data-grid-premium/src/hooks/features/aggregation/gridAggregationUtils.ts
+++ b/packages/x-data-grid-premium/src/hooks/features/aggregation/gridAggregationUtils.ts
@@ -86,18 +86,16 @@ export const mergeStateWithAggregationModel =
     aggregation: { ...state.aggregation, model: aggregationModel },
   });
 
-export const getAggregationRules = ({
-  columnsLookup,
-  aggregationModel,
-  aggregationFunctions,
-}: {
-  columnsLookup: GridColumnRawLookup;
-  aggregationModel: GridAggregationModel;
-  aggregationFunctions: Record<string, GridAggregationFunction>;
-}) => {
+export const getAggregationRules = (
+  columnsLookup: GridColumnRawLookup,
+  aggregationModel: GridAggregationModel,
+  aggregationFunctions: Record<string, GridAggregationFunction>,
+) => {
   const aggregationRules: GridAggregationRules = {};
 
-  Object.entries(aggregationModel).forEach(([field, columnItem]) => {
+  // eslint-disable-next-line guard-for-in
+  for (const field in aggregationModel) {
+    const columnItem = aggregationModel[field];
     if (
       columnsLookup[field] &&
       canColumnHaveAggregationFunction({
@@ -111,7 +109,7 @@ export const getAggregationRules = ({
         aggregationFunction: aggregationFunctions[columnItem],
       };
     }
-  });
+  }
 
   return aggregationRules;
 };
diff --git a/packages/x-data-grid-premium/src/hooks/features/aggregation/useGridAggregation.ts b/packages/x-data-grid-premium/src/hooks/features/aggregation/useGridAggregation.ts
index 2a9e12601509a..8b41493cc2b96 100644
--- a/packages/x-data-grid-premium/src/hooks/features/aggregation/useGridAggregation.ts
+++ b/packages/x-data-grid-premium/src/hooks/features/aggregation/useGridAggregation.ts
@@ -103,11 +103,11 @@ export const useGridAggregation = (
 
     const aggregationRules = props.disableAggregation
       ? {}
-      : getAggregationRules({
-          columnsLookup: gridColumnLookupSelector(apiRef),
-          aggregationModel: gridAggregationModelSelector(apiRef),
-          aggregationFunctions: props.aggregationFunctions,
-        });
+      : getAggregationRules(
+          gridColumnLookupSelector(apiRef),
+          gridAggregationModelSelector(apiRef),
+          props.aggregationFunctions,
+        );
 
     // Re-apply the row hydration to add / remove the aggregation footers
     if (!areAggregationRulesEqual(rulesOnLastRowHydration, aggregationRules)) {
diff --git a/packages/x-data-grid-premium/src/hooks/features/aggregation/useGridAggregationPreProcessors.tsx b/packages/x-data-grid-premium/src/hooks/features/aggregation/useGridAggregationPreProcessors.tsx
index b0f1ab6933ae0..5ae196fb91ce1 100644
--- a/packages/x-data-grid-premium/src/hooks/features/aggregation/useGridAggregationPreProcessors.tsx
+++ b/packages/x-data-grid-premium/src/hooks/features/aggregation/useGridAggregationPreProcessors.tsx
@@ -36,11 +36,11 @@ export const useGridAggregationPreProcessors = (
     (columnsState) => {
       const aggregationRules = props.disableAggregation
         ? {}
-        : getAggregationRules({
-            columnsLookup: columnsState.lookup,
-            aggregationModel: gridAggregationModelSelector(apiRef),
-            aggregationFunctions: props.aggregationFunctions,
-          });
+        : getAggregationRules(
+            columnsState.lookup,
+            gridAggregationModelSelector(apiRef),
+            props.aggregationFunctions,
+          );
 
       columnsState.orderedFields.forEach((field) => {
         const shouldHaveAggregationValue = !!aggregationRules[field];
@@ -76,11 +76,11 @@ export const useGridAggregationPreProcessors = (
     (value) => {
       const aggregationRules = props.disableAggregation
         ? {}
-        : getAggregationRules({
-            columnsLookup: gridColumnLookupSelector(apiRef),
-            aggregationModel: gridAggregationModelSelector(apiRef),
-            aggregationFunctions: props.aggregationFunctions,
-          });
+        : getAggregationRules(
+            gridColumnLookupSelector(apiRef),
+            gridAggregationModelSelector(apiRef),
+            props.aggregationFunctions,
+          );
 
       const hasAggregationRule = Object.keys(aggregationRules).length > 0;