Have you tried DuckDB?

[Alex-Monahan]

Howdy! Fun project!

Have you tried using DuckDB? It uses Postgres syntax (it even uses a fork of the Postgres parser), but is ~20x faster than SQLite per CPU core and supports multithreading. Might speed things up!

https://.duckdb.org

[chunky]

I just went to duckdb's website and tried the simplest possible CTE:
WITH RECURSIVE a(n) AS (SELECT 1 UNION ALL SELECT n+1 FROM a WHERE n<100)
SELECT * FROM a;

https://duckdb.org/demo/

In PostgreSQL and SQLite, that outputs 100 rows. On DuckDB's website, it outputs 1. This raytracer is entirely oriented around that working properly.