Author here.

I built this because I wanted a switcher that did nothing at all when I was not using it, and I could not find one. The ones I tried were keeping previews warm, or had a preferences window to work through, or had something ticking along whether or not I was switching windows. So most of the post is about whether this one actually does nothing, rather than about the app.

The part I did not expect: while the panel is on screen the process holds about 96 MB of graphics memory. It is the same 96 MB whether the list has three rows or thirty, because it is a render pool taken in one go rather than surfaces sized to fit the window. Turning off the blur and the shadow does not reduce it. It comes out 4 MB higher, which is noise. That is in the post because it looks alarming in Activity Monitor and I would rather explain it than have someone find it.

Raising a window needs three private SkyLight symbols. They are named in the post. yabai and Hammerspoon have used and documented them publicly for years so there is nothing secret about them, but they are why it cannot be sandboxed and will not be on the App Store.

alt-tab-macos is free, open source and the better choice for most people. If you have not tried it, try that first.