add sig cache

[shamb0t]

Adds cache for known signatures

[aphelionz]

This looks good to me, nice catch with the v0 signatures too.

I'm wondering if you can try using the hrtime method I did here in my first attempt in the tests to see what kind of perf improvement we get?

[aphelionz]

Eschewing the hrtime request, just having tests at all would be great. I'd be happy to write them if you'd like.

[aphelionz]

LGTM!