I was getting much worse performance than node/mysql2 in a web app benchmarked by k6. The problem seemed to be this driver, so I made a crude benchmark which seems to agree with what I was seeing.
https://github.com/kswope/deno-mysql-bench
Here's a preview of the kind of results I'm getting
deno-mysql-bench> deno run --allow-net ./deno/index.ts
INFO connecting localhost:3306
INFO connected to localhost:3306
default: 7402ms
INFO close connection
deno-mysql-bench> node node/index.js
default: 996.609ms