ecode [0] is ridiculously fast -- makes Zed feel like molasses -- and quite customizable. It's still early in development and mostly just made by one guy (who is also developing the GUI framework used), so progress is slow and there are some rough edges, but it has all the important stuff and quite a few niceties too. Really cool project, reminds me of Sublime.

[0] https://github.com/SpartanJ/ecode/