diff --git a/x-pack/plugins/security_solution/public/common/containers/source/index.test.tsx b/x-pack/plugins/security_solution/public/common/containers/source/index.test.tsx
new file mode 100644
index 0000000000000..e81b52f281519
--- /dev/null
+++ b/x-pack/plugins/security_solution/public/common/containers/source/index.test.tsx
@@ -0,0 +1,30 @@
+/*
+ * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+ * or more contributor license agreements. Licensed under the Elastic License;
+ * you may not use this file except in compliance with the Elastic License.
+ */
+
+import { IndexField } from '../../../../common/search_strategy/index_fields';
+import { getBrowserFields } from '.';
+import { mockBrowserFields, mocksSource } from './mock';
+
+describe('source/index.tsx', () => {
+  describe('getBrowserFields', () => {
+    test('it returns an empty object given an empty array', () => {
+      const fields = getBrowserFields('title 1', []);
+      expect(fields).toEqual({});
+    });
+
+    test('it returns the same input with the same title', () => {
+      getBrowserFields('title 1', []);
+      // Since it is memoized it will return the same output which is empty object given 'title 1' a second time
+      const fields = getBrowserFields('title 1', mocksSource.indexFields as IndexField[]);
+      expect(fields).toEqual({});
+    });
+
+    test('it transforms input into output as expected', () => {
+      const fields = getBrowserFields('title 2', mocksSource.indexFields as IndexField[]);
+      expect(fields).toEqual(mockBrowserFields);
+    });
+  });
+});
diff --git a/x-pack/plugins/security_solution/public/common/containers/source/index.tsx b/x-pack/plugins/security_solution/public/common/containers/source/index.tsx
index 2cc1c75015e07..47e550b2ced0f 100644
--- a/x-pack/plugins/security_solution/public/common/containers/source/index.tsx
+++ b/x-pack/plugins/security_solution/public/common/containers/source/index.tsx
@@ -4,7 +4,6 @@
  * you may not use this file except in compliance with the Elastic License.
  */
 
-import { set } from '@elastic/safer-lodash-set/fp';
 import { keyBy, pick, isEmpty, isEqual, isUndefined } from 'lodash/fp';
 import memoizeOne from 'memoize-one';
 import { useCallback, useEffect, useMemo, useRef, useState } from 'react';
@@ -55,15 +54,31 @@ export const getIndexFields = memoizeOne(
   (newArgs, lastArgs) => newArgs[0] === lastArgs[0] && newArgs[1].length === lastArgs[1].length
 );
 
+/**
+ * HOT Code path where the fields can be 16087 in length or larger. This is
+ * VERY mutatious on purpose to improve the performance of the transform.
+ */
 export const getBrowserFields = memoizeOne(
-  (_title: string, fields: IndexField[]): BrowserFields =>
-    fields && fields.length > 0
-      ? fields.reduce<BrowserFields>(
-          (accumulator: BrowserFields, field: IndexField) =>
-            set([field.category, 'fields', field.name], field, accumulator),
-          {}
-        )
-      : {},
+  (_title: string, fields: IndexField[]): BrowserFields => {
+    // Adds two dangerous casts to allow for mutations within this function
+    type DangerCastForMutation = Record<string, {}>;
+    type DangerCastForBrowserFieldsMutation = Record<
+      string,
+      Omit<BrowserField, 'fields'> & { fields: Record<string, BrowserField> }
+    >;
+
+    // We mutate this instead of using lodash/set to keep this as fast as possible
+    return fields.reduce<DangerCastForBrowserFieldsMutation>((accumulator, field) => {
+      if (accumulator[field.category] == null) {
+        (accumulator as DangerCastForMutation)[field.category] = {};
+      }
+      if (accumulator[field.category].fields == null) {
+        accumulator[field.category].fields = {};
+      }
+      accumulator[field.category].fields[field.name] = (field as unknown) as BrowserField;
+      return accumulator;
+    }, {});
+  },
   // Update the value only if _title has changed
   (newArgs, lastArgs) => newArgs[0] === lastArgs[0]
 );