Nice and simple with some interesting features, only.. not confident enough to use it when there's no info re saving/restoring sessions - and nowhere I can find to ask questions about this??

Unable to drag tab from one window to another window.

It cannot do that much. There are better extensions for the same functionality and more.

That could be an advantage if you're looking for a minimalstic tool.

I like what this add-on can do but it is EXTREMELY laggy and unresponsive. I even turned off tab previews and tab details which helped a bit but it's still extremely laggy. I'm running on a MacBook Pro 2019 model with an 8 core CPU, and when I open this extension's popup window, it nearly pegs an entire core. I'm usually around 5-6% average usage on my CPU cores during normal browsing, but when I open the popup it shoots up to 15-25% average. You do the math. To be fair, I have 8 windows open across 2 Spaces, but each window has less than 12 tabs, and honestly if you're using a manager extension like this you've probably got at least half as many windows and tabs as me. I hope the developer works on improving the performance of this extension. It's very nice and only hindered by the performance. I will still use it.

edit: thank you developer for the response. I look forward to any and all performance improvements!

A pop up size is too small and inconvenient with my 600 tabs. Just consider simple task of moving 5 tabs from Window 7 to Window 13.
The app makes it impossible to handle.