diff --git a/TEST.md b/TEST.md
index 7dcf74e..85e770b 100644
--- a/TEST.md
+++ b/TEST.md
@@ -33,5 +33,5 @@
   - Added complex Area Selection, Copy/Paste, and Row Deletion.
   - Successfully decoupled dynamic UI states (like `.dt-cell-selected`) from the declarative binding framework. We now use manual DOM manipulation (`applySelectionUI`) during `refresh` to sync states.
   - This manual sync completely prevents "Dependency Floods" where scrolling would trigger heavy `$class` evaluations on every cell. We maintained the Zero-Scan status while supporting rich interactions.
-  - Fixed a VirtualScroll jumping bug at row 70+ by re-enabling `onItemUpdate` so VirtualScroll correctly learns the 40px row height instead of using its 32px default.
+  - Fixed a VirtualScroll jumping bug at row 70+ by introducing an `options.itemHeight` configuration to the base `VirtualScroll` module. `DataTable` now explicitly passes `{ itemHeight: 40 }` during instantiation. This elegantly bypasses expensive `getComputedStyle` and `offsetHeight` measurements while perfectly seeding the internal height map, completely eliminating layout thrashing and scrolling jank without requiring users to pollute their business data with `_itemHeight`.
   - **Scroll Initiation Fix**: Removed the `setTimeout` wrapper around `vs.init` during `reset`. Previously, the first scroll often hit a "blank wall" because VirtualScroll's internal metrics hadn't finished initializing when the user made their first swift scroll motion. Synchronous initialization resolved this completely.
diff --git a/src/scroll.js b/src/scroll.js
index 8e750c1..27715d0 100644
--- a/src/scroll.js
+++ b/src/scroll.js
@@ -1,7 +1,7 @@
 import { VirtualScroll } from '@web/base';
 
 export const createScrollManager = (container, state, onRenderedListChange) => {
-    const vs = VirtualScroll();
+    const vs = VirtualScroll({ itemHeight: 40 });
     let scrollEl = null;
 
     const refresh = () => {
@@ -29,19 +29,6 @@ export const createScrollManager = (container, state, onRenderedListChange) => {
         reset: (list) => {
             state._listStartIndex = 0;
             state._renderedList = vs.reset(list, scrollEl || container) || [];
-            
-            // Performance Fix: Seed the VirtualScroll average height to 40px BEFORE init().
-            // This entirely eliminates the need for onItemUpdate (which causes layout thrashing
-            // during fast scrolls) while still perfectly fixing the "row 70 jump" bug caused
-            // by VirtualScroll's 32px default assumption.
-            const mockNode = document.createElement('div');
-            mockNode.style.marginTop = '0px';
-            mockNode.style.marginBottom = '0px';
-            Object.defineProperty(mockNode, 'offsetHeight', { value: 40 });
-            document.body.appendChild(mockNode);
-            vs.update(0, mockNode);
-            document.body.removeChild(mockNode);
-
             if (state.list === list) {
                 vs.init(list, refresh);
             }