Interesting. Maybe I should have tried to configure it better?
In the end, doing a rewrite of the core features allowed me to fine tune the technical choices to work extremely well on Windows (where fork is slow) while adding SQL for both the command history and query format, so hopefully I didn't just reinvent the wheel :)
ble.sh has a vast array of configuration options. By disabling features I didn't like or need I was able to make it run pretty fast and responsive.