Your comments

Since 7 years I'm using smartgit, I never faced a perfomance issue because I've my 5-10 repos open.

But several times a WEEK, I need to click click click click -- oups not this one -- click click 5-10 times EVERY time I OPEN a repo.

This is driving me crazy.
Your argument is not valid: nothing prevents you to "Ctrl-A -> open", or right-click on a group to open its 25 repos. If the number of open repository is a problem, you may just popup a notification when (a configurable number of) N repos are simultaneously opened, or/and display a warning the first time it happens.

Please. I really appreciate the smargit UX in general for its efficiency, but that's IMHO the most annoying feature.

Ultimately, I do want to open one more repo. So I'll do. I'm just looking for the most efficient way of archiving it. Currently I ctrl-select the N repos currently open, plus the new one, and right-click "open". Really boring. But in my case, it's the best option. Usually, it's a worktree repo, and I want all repos linked to a project be in the same window. I cannot manage open-in-a-new-window IE6 style. I got lost and loose even more time.

Rgds