@mflatt I don’t understand how this code is supposed to work: https://github.com/racket/racket7/blob/master/racket/src/expander/boot/handler.rkt#L202

shouldn’t that cons produce something that is by definition only accessible via the weak box?

and therefore, the weak box can be immediately cleared by the GC

The weak box can indeed be cleared immediately by the GC. The intent is to cache values only between GCs.

Ok, I think (but am not sure) that @cadr is seeing a performance issue there with Pycket, because we rarely get any cache hits