IO bound and particularly network bound code is common too. The first fix I'd try with network bound code is to either eliminate the network call (local cache? turn a microservice into a library?) or to batch operations.
> Last step is to multithread it if it needs even more juice
In web app land, this is fraught with peril if you're doing it on the server, because it means your code is now competing for n times the resources. Often it's better for one request to take a long time if it means it's using a more predictable amount of memory, not causing other requests to time out, not exhausting your DB connection pool, etc.
I imagine that systems programming is similar in some ways and that's why multithreading is the last resort, just mentioning it because it's easy to shoot oneself in the foot with parallelism.
