consider using xi-core

[xi-core](https://github.com/xi-editor/xi-editor) is a backend for text editors with a focus on being fast and modular i do not represent them in anyway but nonetheless I think this is a good idea for both projects

Start by reading the xi-core project linked in the issue and reviewing how this text editor currently handles its editing backend. Determine whether adopting xi-core is feasible and define the integration scope before proposing implementation work; done would require an agreed approach and a working integration.

Written by the indexing model from the issue text.