OK, I know this post is over 7 months old, but how are you able to keep TextMate working on current versions of OS X? For me TextMate has been mostly unusable for a couple of years now due to conflicts with the OS making it super slow.
Late last year I finally came to terms that TextMate wasn't coming back and I had to find a new favorite text editor. So far I'm leaning toward SublimeText though I hear from longtime users that it's going the way of TextMate so I'm hesitating to go all in on it.
TextMate 2 has been working well for my needs and I haven't encountered any particular slowdowns. I'm currently running version 2.0.23 on a few different Intel and M1 Macs without any issues.
Your post did make me look into the development situation for TextMate and it's definitely depressing. Almost nothing has happened in the git repository for a few years now. So, it's probably only a matter of time before I need to find something new.
I don't really want or need a full IDE. I mainly write Python code for data analysis (I'm a researcher in academia) and small GUI programs, or in some cases Fortran code when better performance is needed. I value apps that "feel" like a real Mac app as aposed to cross-platform ones that don't really behave like I expect.
Two apps that come close to replacing TextMate for me are BBEdit and Visual Studio Code. BBEdit feels a lot like TextMate It's lightweight and a native app. It has most of the features I like in TextMate except for one big one, the multiple carets at arbitrary positions. BBEdit is a subscription app on the App Store but has a perpetual license available on their website. Visual Studio Code is an open source app from Microsoft. It's an Electron app though, so it doesn't feel entirely like a true Mac app. It works well and has a lot of features as well as an active community. To me it almost feels too feature rich, to the point of being intimidating for my needs, but a few of my coworkers use it and love it. This also comes with some bloat. Editing the same Fortran code in VS Code, BBEdit, and TextMate on my M1 Pro MacBook Pro running Ventura 13.2, I see TextMate using 86MB of memory, BBEdit using 106MB, and VS Code using 665MB. I'm not short on RAM, but it's worth pointing out.
In the end, I'm not sure what I'll do.