Golang's concurrency primitives work against the grain here, as far as the design of high performance caches. Ristretto resorts to using sync.Pool as a sloppy queue mechanism to log gets, which apparently works but is not part of the official semantics, and may prove brittle in the future. It's also just sadly still far off from what's possible using bare metal techniques in c.

I have a design I'm working on that I think may rival or surpass Ristretto, though it also benefits greatly from immutability. The TL;DR is a power of two choices hash table, where each bucket holds a couple cache lines of count-min-sketch approximations similar to TinyLFU, as well as a few value slots, and uses a bucket local counter reset mechanism. It should run very fast due to minimal contention, but the open question is what negative impacts a bucket local reset might have. My response to this is simple and conservative: I'm oversizing the count-min-sketch vectors and counters slightly for some breathing room.