I have been using Emacs for about 10 years and am getting tired of its idiosyncrasies and performance hiccups. I tried a bunch of alternative editors with scripting support (most recent being TextAdept) but none of them seem to have a native Undo-Tree [1] features or an API powerful enough to build it. So, I am asking here: are there any non-Electron based editors with a reasonably decent scripting layer or a plugin system, and Undo Tree functionality.
PS: I know that Vim has it, but I've never been able to get comfortable with Vim and other Vim-like editors.
[1]: https://github.com/casouri/vundo
There's also been some good advice on dealing with your performance hiccups. I'd like to add that you should look at what packages you're running and what you're loading from your init file. In my 30ish years of experience using Emacs (omg, yes 30 :(), negative performance has almost always been directly related to packages, and not Emacs itself. Case in point... in the early 90s I was having issues with syntax highlighting multi-megabyte (as in more than 1 and less than 10) files. Changing font locking (syntax highlighting) to use this new fangled "lazy-lock" package fixed all my issues. I don't think I've had a performance issue since. So, look at your init file. Cut some chaff out of there. Got a fancy VCS front end? Don't use it for a couple of weeks. Performance issues go away? Submit a thoughtful bug report; help yourself and others.
If you do want to switch, do it. But give VIM another try, and specifically Neovim. Personally, I recently challenged myself to do a "Lua-only-no-arrow-keys Neovim" and I've been loving it. I've used vi/VIM as long as I've used Emacs, but I'm not by any stretch a "power user". So, maybe I've had a bit of a head-start being comfortable with movement and selection, etc. But everything else has made migration easy. The online resources, the inline help, the package ecosystem; all of it. Even discovering the "toy" packages has been fun. Want ducks wandering around your active buffer? Yeah, Neovim has that.
"IDE" fads come and go, myself and many others on HN can probably give you quite a list, but as far as editors go Emacs and VIM/Neovim are in a class by themselves. Take advantage of what they have to offer, even if it means diving a bit deeper.