It appears that whilst bootstrapping a node, Tezos will only make use of a single CPU. Is there a reason for this and would Tezos benefit from any parallelisation?
It is not trivial to achieve the bootstrap phase in parallel. Indeed, while bootstrapping, you have a dependency on the availability of the last context (ledger state) used to compute the next one, and so on.
However, there is still room for improvement on the node performances and we are working on it.