LiChess Monthly Database

Mr. Thibault, the problem is that that happened 61 times... kingdon1 checkmated sf in 5 moves every time, 61 games. However, this is not the correct place to report cheating and sandbagging.
Use this instead: lichess.org/report

I still think most of these are legit :) Ultrabullet allows for quick checkmate if the opponent is not careful.

@aryadew try pgn-extract!
www.cs.kent.ac.uk/people/staff/djb/pgn-extract/
www.cs.kent.ac.uk/people/staff/djb/pgn-extract/help.html#suppress

When I compiled the book for @AtomicChessBot, I processed all monthly atomic databases. This took cca. 5 hours using github.com/niklasf/python-chess which is in a high level language therefore its game parser is not of high performance ( but of high quality though ).

The trick you can apply, is to filter first the PGNs based only on PGN headers. This can be done very fast, even in a high level language. In my case I only needed games where both players were >2200 rated. This let me get rid of tons of non meaningful games without having to use the python-chess parser. If I had used python-chess for all games, well yes, then it would have taken ages to finish this job.

So try to be smart about your parser and get rid of unwanted games based on PGN headers first.

This is the tool I used to build the atomic book:

github.com/lichapibot/cbuild

Thank you all for your helpful comments and suggestions. Appreciated !