[foota]

I think this is more like caching the regex than creating it at compile time? Load time I think is basically runtime. I think lisp can be loaded and then rehydrated later, but I'm not sure how common that is.

[burntsushi]

Hard to say exactly since I don't have experience with cl-ppcre, but this line seems to suggest something is actually happening at complile time:

> This happens if the compiler can determine that the regular expression (no matter if it's a string or an S-expression) is constant at compile time

If this were just a run of the mill caching mechanism, then whether the pattern was a constant at compile time wouldn't matter.