Executing fasls is cool, but they will start from a new empty image, and loading fasls is actually kind of slow, so if you use lots of libraries rather than write a trivial example, that may consume hundreds of milliseconds before the program actually starts. Then again, this supposes you compiled everything into a single .fasl (which ASDF makes easy). But that will be a big fasl for each program; if you want to load from libraries, then there's also the overhead of setting up and using ASDF itself, which can also be in the hundreds of milliseconds. I can imagine many ways to improve the situation, but none are cheap (e.g. implement a background daemon to serve ready executables and/or watch the source registry for modified source; or break compatibility with the entire ASDF setup, angrying the entire community).