Microsoft’s new Outlook for Windows lags when users click a Windows 11 notification. Instead of opening the email instantly, the app spends about 10 seconds loading the full inbox before displaying the message. The delay exposes a deeper issue: the new version runs on Web View2, a Chromium‑based engine that slows every interaction.

Outlook Classic, the long‑running Win32 desktop app, opens the targeted email in a fraction of a second. Classic uses only about 117‑148 MB of RAM at idle, whereas the new Outlook consumes 490‑636 MB and runs ten separate Web View2 processes. The larger memory draw and process overhead explain why the web‑based version stalls for developers who rely on instant notifications daily workflows.

Microsoft has pushed the new Outlook as the future of email on Windows, even moving the legacy UWP Mail and Calendar apps offline by late 2024. The company postponed the forced opt‑out deadline to March 2027, signaling that the app still requires refinement. Recent updates added folder search, shared mailbox support, and Copilot integration, but core performance gaps remain for power users.

The 10‑second lag remains a stark reminder that moving email to a browser engine incurs real costs. For teams that depend on quick access to incoming messages, the classic app still offers the speed and reliability that the new Outlook lacks. Microsoft must resolve these delays before the web‑based version can replace the legacy client for enterprise users worldwide.