I'm currently using this in a binary format for serializing dynamic JSON-like values that I invented and am implementing in Rust. I will release it as open source sometime next year.
So it would be sweet to instead use a format for which it is possible to write fast decoders
I usually use something I came up with years ago where the low 2 or 3 bits are the length - 1 in bytes. It's more compact and can be serialized/deserialized without branches in the common case. It uses the count leading zeroes instruction for encoding. I'm sure somebody else has come up with the idea as well.
The downside is you can only represent 30 bits for u32 and 61 for u64. In many cases you know you don't have values that large, so it's fine.
If you're encoding arrays of integers, Lemire has a library that uses vector instructions to encode them in the optimal number of bits. That's even better, but the use cases are far more restricted.