perf(datagrid): serve row count from cache to smooth scrolling

CHANGELOG.md

@@ -9,6 +9,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Changed
 
+- Data grid now serves the row count from its existing cache instead of recomputing it on every layout pass, reducing CPU churn while scrolling large result sets.
 - Typing in the sidebar table search stays responsive on databases with thousands of tables; filtering runs after a short pause instead of on every keystroke.
 
 ### Fixed

TablePro/Views/Results/DataGridCoordinator.swift

@@ -109,7 +109,6 @@ final class TableViewCoordinator: NSObject, NSTableViewDelegate, NSTableViewData
     let cellFactory = DataGridCellFactory()
     let cellRegistry: DataGridCellRegistry
     let columnPool = DataGridColumnPool()
-    let tableRowsController = TableRowsController()
     let selectionController = GridSelectionController()
     var overlayEditor: CellOverlayEditor?
     var overlayViewer: CellOverlayViewer?
@@ -234,7 +233,6 @@ final class TableViewCoordinator: NSObject, NSTableViewDelegate, NSTableViewData
             }
             tableView.reloadData()
         }
-        tableRowsController.detach()
         delegate = nil
         activeFKPreviewPopover?.close()
         clearFKPreviewState()
@@ -713,7 +711,7 @@ final class TableViewCoordinator: NSObject, NSTableViewDelegate, NSTableViewData
     // MARK: - NSTableViewDataSource
 
     func numberOfRows(in tableView: NSTableView) -> Int {
-        sortedIDs?.count ?? tableRowsProvider().count
+        sortedIDs?.count ?? cachedRowCount
     }
 }
 

TablePro/Views/Results/DataGridView.swift

@@ -109,7 +109,6 @@ struct DataGridView: NSViewRepresentable {
         context.coordinator.tableView = tableView
         installSelectionOverlay(tableView: tableView, coordinator: context.coordinator)
         context.coordinator.attachScrollObservers(scrollView: scrollView)
-        context.coordinator.tableRowsController.attach(tableView)
         context.coordinator.tableRowsProvider = tableRowsProvider
         context.coordinator.tableRowsMutator = tableRowsMutator
         context.coordinator.paginationOffsetProvider = paginationOffsetProvider
@@ -426,7 +425,6 @@ struct DataGridView: NSViewRepresentable {
         coordinator.persistColumnLayoutToStorage()
         coordinator.settingsCancellable = nil
         coordinator.themeCancellable = nil
-        coordinator.tableRowsController.detach()
     }
 
     func makeCoordinator() -> TableViewCoordinator {

TablePro/Views/Results/Extensions/DataGridView+CellCommit.swift

@@ -26,14 +26,10 @@ extension TableViewCoordinator {
             in: tableView,
             schema: identitySchema
         ) else { return }
-        if case .cellChanged = delta {
-            tableRowsController.apply(.cellChanged(row: row, column: tableColumnIndex))
-        } else {
-            tableView.reloadData(
-                forRowIndexes: IndexSet(integer: row),
-                columnIndexes: IndexSet(integer: tableColumnIndex)
-            )
-        }
+        tableView.reloadData(
+            forRowIndexes: IndexSet(integer: row),
+            columnIndexes: IndexSet(integer: tableColumnIndex)
+        )
     }
 
     @discardableResult