This was posted back in March, but it's news to me:
A long-running project has been JIT-compiling SQL queries in PostgreSQL by making use of LLVM's just-in-time compilation support, rather than passing SQL queries through Postgres' interpreter. With the LLVM JIT'ed queries, more efficient code is generated by being able to make more use of run-time information and can especially help in increasing the performance of complex SQL queries.
JIT-compiling expressions for PostgreSQL has been found to be up to ~20%+ faster in database tests like TPC-H. Creating indexes was found to be even 5~19% faster with this JIT mode
Hopefully this feature will progress quick enough to land in Postgres 11. 🙏