Why does Windows 11 feel so much slower after using Linux?

I'd start with the graphics driver. A fresh Windows installation may not have the right driver set up yet, and that could affect both display detection and how smooth the desktop feels. Check Windows Update and the laptop manufacturer's driver downloads, then see whether the monitor is detected.

It's also worth checking whether updates were still running during the comparison. That doesn't explain every possible problem, but it gives you a cleaner test before deciding the system is just slow.

Some of that sounds like a workflow mismatch rather than a bug. If you're used to GNOME's workspaces and shortcuts, Windows virtual desktops can feel awkward even when they're working as designed. Shortcut conflicts are frustrating too, especially if you have a setup you already like.

Windows 11 can also be snappy and stable, so I wouldn't assume the experience is universal. Hardware, drivers, updates and individual preferences can make a big difference. The laptop model and whether Windows was fully updated would be useful details for troubleshooting.

If Ubuntu does what you need, there's nothing wrong with sticking with it. Having a desktop workflow you like and a straightforward way to update software matters more day to day than whether one system looks better on paper.

The battery result is useful too, though I'd treat it as specific to that laptop and usage rather than a general rule about either OS.