There is disclosed in an example, an endpoint apparatus for an interconnect, comprising: a mechanical and electrical interface to the interconnect; and one or more logic elements comprising an interface vector engine to: receive a first scalar transaction for the interface; determine that the first scalar transaction meets a criterion for vectorization; receive a second scalar transaction for the interface; determine that the second transaction meets the criterion for vectorization; vectorize the first scalar transaction and second scalar transaction into a vector transaction; and send the vector transaction via the electrical interface