I think this would read better with the order slightly changed:

> Since the exact type and size of a frame's components are known ahead of time, we can avoid the `binary` package's convenience `Read` and `Write` wrappers (and their extraneous interface lookups and conversions) and instead call the appropriate `binary.BigEndian` methods directly.

This paragraph and the following one sound like micro-optimizations to me.  Were these optimizations put in place to cut down an actual bottleneck?  Were they discovered via, say, profiling?  If so, would it be useful to note that somewhere around here?