Back in 2014 Dropbox announced the Pyston project as an open-source JIT compiler to Python focusing upon maximum performance. With this newest Pyston release (v0.6.1) they are now 95% faster than CPython, but Dropbox is ending their involvement in the project…

Source: Phoronix – Pyston Now 95% Faster Than CPython, But Dropbox Just Stopped Supporting It