fix: resolve high CPU usage and memory leaks at idle (#368) (#369)

* perf: fix high CPU usage and memory leaks at idle (#368)

- Guard updateSession against no-op writes using isContentViewEquivalent
- Skip onStateChanged callback for routine healthy↔checking ping cycles
- Move lastActiveAt updates through guarded updateSession (no-op when only timestamp changes)
- Track all driver operations in queriesInFlight to prevent health monitor TOCTOU races
- Fix activeCoordinators memory leak by moving registerForPersistence to markActivated
- Replace loadConnections() disk I/O in ContentView.init with in-memory lookup
- Change WindowLifecycleMonitor to weak NSWindow references with purgeStaleEntries
- Guard redundant .connecting status writes during reconnect attempts
- Add [weak self] to nested DispatchQueue.main.async in SQLEditorCoordinator
- Move prefetch DB fetch off MainActor with tracked task and dedup guard
- Move Keychain migration to Task.detached for non-blocking startup
- Move plugin bundle.load() off MainActor via nonisolated static method
- Use targeted reloadData for FK columns instead of full table reload
- Debounce JSON syntax highlighting with 100ms DispatchWorkItem
- Replace O(n²) undo batch index shift with O(n log n) binary search

* perf: scope observation to per-connection version counters (HIGH-1)

Add connectionStatusVersions dictionary with per-connection counters.
ContentView and MainContentView now observe only their connection's
counter instead of the global connectionStatusVersion, eliminating
cross-connection re-render overhead when multiple connections are open.

* fix: address PR review feedback from CodeRabbit

- Fix FK column reload to use display-order indices (respects user column reordering)
- Remove force-unwrap in JSON highlight debounce (use local variable)
- Add purgeStaleEntries to connectionId(for:) and window(for:) in WindowLifecycleMonitor
- Fix audit doc date typo and inconsistent checkbox states

* chore: exclude performance audit doc from PR

* perf: mark internal bookkeeping properties with @ObservationIgnored

Author: datlechin

TablePro/AppDelegate.swift

@@ -56,7 +56,9 @@ class AppDelegate: NSObject, NSApplicationDelegate {
         let passwordSyncExpected = syncSettings.enabled && syncSettings.syncConnections && syncSettings.syncPasswords
         let previousSyncState = UserDefaults.standard.bool(forKey: KeychainHelper.passwordSyncEnabledKey)
         UserDefaults.standard.set(passwordSyncExpected, forKey: KeychainHelper.passwordSyncEnabledKey)
-        KeychainHelper.shared.migrateFromLegacyKeychainIfNeeded()
+        Task.detached(priority: .utility) {
+            KeychainHelper.shared.migrateFromLegacyKeychainIfNeeded()
+        }
         if passwordSyncExpected != previousSyncState {
             Task.detached(priority: .background) {
                 KeychainHelper.shared.migratePasswordSyncState(synchronizable: passwordSyncExpected)

TablePro/ContentView.swift

@@ -40,7 +40,7 @@ struct ContentView: View {
         if let tableName = payload?.tableName {
             defaultTitle = tableName
         } else if let connectionId = payload?.connectionId,
-                  let connection = ConnectionStorage.shared.loadConnections().first(where: { $0.id == connectionId }) {
+                  let connection = DatabaseManager.shared.activeSessions[connectionId]?.connection {
             let langName = PluginManager.shared.queryLanguageName(for: connection.type)
             defaultTitle = "\(langName) Query"
         } else {
@@ -102,7 +102,7 @@ struct ContentView: View {
                     columnVisibility = .detailOnly
                 }
             }
-            .onChange(of: DatabaseManager.shared.connectionStatusVersion, initial: true) { _, _ in
+            .onChange(of: (payload?.connectionId ?? currentSession?.id).flatMap { DatabaseManager.shared.connectionStatusVersions[$0] }, initial: true) { _, _ in
                 let sessions = DatabaseManager.shared.activeSessions
                 let connectionId = payload?.connectionId ?? currentSession?.id ?? DatabaseManager.shared.currentSessionId
                 guard let sid = connectionId else {

TablePro/Core/ChangeTracking/DataChangeManager.swift

@@ -88,6 +88,21 @@ final class DataChangeManager {
         return true
     }
 
+    /// Binary search: count of elements in a sorted array that are strictly less than `target`.
+    /// Used for O(n log n) batch index shifting instead of O(n²) nested loops.
+    private static func countLessThan(_ target: Int, in sorted: [Int]) -> Int {
+        var lo = 0, hi = sorted.count
+        while lo < hi {
+            let mid = (lo + hi) / 2
+            if sorted[mid] < target {
+                lo = mid + 1
+            } else {
+                hi = mid
+            }
+        }
+        return lo
+    }
+
     /// Undo/redo manager
     private let undoManager = DataChangeUndoManager()
 
@@ -414,18 +429,20 @@ final class DataChangeManager {
 
         pushUndo(.batchRowInsertion(rowIndices: validRows, rowValues: rowValues))
 
-        for deletedIndex in validRows.reversed() {
-            var shiftedIndices = Set<Int>()
-            for idx in insertedRowIndices {
-                shiftedIndices.insert(idx > deletedIndex ? idx - 1 : idx)
-            }
-            insertedRowIndices = shiftedIndices
+        // Single-pass shift using binary search instead of O(n²) nested loop
+        let sortedDeleted = validRows.sorted()
 
-            for i in 0..<changes.count {
-                if changes[i].rowIndex > deletedIndex {
-                    changes[i].rowIndex -= 1
-                }
-            }
+        var newInserted = Set<Int>()
+        for idx in insertedRowIndices {
+            let shiftCount = Self.countLessThan(idx, in: sortedDeleted)
+            newInserted.insert(idx - shiftCount)
+        }
+        insertedRowIndices = newInserted
+
+        for i in 0..<changes.count {
+            let rowIndex = changes[i].rowIndex
+            let shiftCount = Self.countLessThan(rowIndex, in: sortedDeleted)
+            changes[i].rowIndex = rowIndex - shiftCount
         }
 
         rebuildChangeIndex()

TablePro/Core/Database/ConnectionHealthMonitor.swift

@@ -246,17 +246,17 @@ actor ConnectionHealthMonitor {
         state = newState
 
         if oldState != newState {
-            // Skip logging for routine healthy ↔ checking cycle (every 30s)
+            // Skip logging and callback for routine healthy ↔ checking ping cycles (every 30s).
+            // These produce no meaningful state change for the UI.
             let isRoutineCycle = (oldState == .healthy && newState == .checking)
                 || (oldState == .checking && newState == .healthy)
             if !isRoutineCycle {
                 Self.logger.log(
                     level: logLevel(for: newState),
                     "Connection \(self.connectionId) health state: \(String(describing: oldState)) -> \(String(describing: newState))"
                 )
+                await onStateChanged(connectionId, newState)
             }
-
-            await onStateChanged(connectionId, newState)
         }
     }
 

TablePro/Core/Database/DatabaseDriver.swift

@@ -311,7 +311,10 @@ extension DatabaseDriver {
 enum DatabaseDriverFactory {
     static func createDriver(for connection: DatabaseConnection) throws -> DatabaseDriver {
         let pluginId = connection.type.pluginTypeId
-        if PluginManager.shared.driverPlugins[pluginId] == nil {
+        // If the plugin isn't registered yet and background loading hasn't finished,
+        // fall back to synchronous loading for this critical code path.
+        if PluginManager.shared.driverPlugins[pluginId] == nil,
+           !PluginManager.shared.hasFinishedInitialLoad {
             PluginManager.shared.loadPendingPlugins()
         }
         guard let plugin = PluginManager.shared.driverPlugins[pluginId] else {