Trivial solution: "fork" the old, fast version of std library code into its own repo and the only change you need is to import that repo instead of "encoding/go

Trivial solution: "fork" the old, fast version of std library code into its own repo and the only change you need is to import that repo instead of "encoding/gob" I did that few times (mostly in the other direction, where I wanted features from unreleased version of Go)