diff --git a/macos/Sources/Features/Terminal/TerminalController.swift b/macos/Sources/Features/Terminal/TerminalController.swift
index 36b863fc0..587510f09 100644
--- a/macos/Sources/Features/Terminal/TerminalController.swift
+++ b/macos/Sources/Features/Terminal/TerminalController.swift
@@ -1119,7 +1119,16 @@ class TerminalController: BaseTerminalController, TabGroupCloseCoordinator.Contr
         // We don't run this logic in fullscreen because in fullscreen this will end up
         // removing the window and putting it into its own dedicated fullscreen, which is not
         // the expected or desired behavior of anyone I've found.
-        if !window.styleMask.contains(.fullScreen) {
+        //
+        // We also only run this when the system tabbing preference is "always",
+        // which is the only scenario AppKit will have auto-tabbed a fresh window
+        // at this point: the tab bar "+" button goes through newWindowForTab
+        // which we route through our own tab logic. This check matters because
+        // accessing `window.tabGroup` materializes the window's tab group
+        // machinery, which takes ~15-20ms and is otherwise not needed during
+        // window creation.
+        if NSWindow.userTabbingPreference == .always,
+           !window.styleMask.contains(.fullScreen) {
             // If we have more than 1 window in our tab group we know we're a new window.
             // Since Ghostty manages tabbing manually this will never be more than one
             // at this point in the AppKit lifecycle (we add to the group after this).