One of the downsides is that implementations like SBCL have a deep integration and need things like a well performing GC implementation - to get this running on specialized game hardware is challenging. The article describes that. Getting over the hurdle of the low-level integration is difficult. The reward comes, when one gets to the point, where the rapid incremental development cycles of Common Lisp, even with connected devices, kicks in.

For the old historic Naughty Dog use case, it was a development system written in Common Lisp on an SGI and a C++ runtime with low-level Scheme code on the Playstation.

> Common Lisp also appears to be a much faster language than I would have blindly assumed.

There are two modes:

1) fast optimized code which allows for some low-level stuff to stay with Common Lisp

2) unoptimized, but natively compiled code, which enables safe (-> the runtime does not crash) interactive and incremental development -> this mode is where much of the software can run nowadays and which is still "fast enough" for many use cases