I don't understand the startup time issue. Tools I use regularly like VS Code, IntelliJ, etc. are constantly running on my machine. I pay their startup cost once per reboot. Once they're running, they open files* as fast as Sublime for me. There maybe other use cases, but startup time feels pointless to me.

*files of sizes I work work. I don't care about gigabyte-sized files; if I do, vim or my existing ST3 license are good enough.