Full Text Search
This uses DuckDB's full text search extention to search through all the post comments. It's freakishly fast for running entirely in your browser. The index is built offline and loaded as parquet files.
It is a bit limited, in that it only searches stems of common words, and no search operators (I think). But still, very fast for ~1.3 million posts.
If you see errors, try a different browser, or turn off the "advanced tracking protection". Not sure why it breaks this script particularly when the javascript is just as horrifying on the other pages, but oh well.