Speed up RsaIdentity decoding
See #377 (closed): In initial quick-and-dirty bootstrap profiling, this function wound up using around 10-13% of our startup time when reading from cache, and the fix was straightforward.
See #377 (closed): In initial quick-and-dirty bootstrap profiling, this function wound up using around 10-13% of our startup time when reading from cache, and the fix was straightforward.