Let me ask you this: let's say you're downstream of a very slow server that is outside of your control. You need to access it, and there's nothing you can do to speed it up. Are you IO bound in this case?
It may be that you didn't sleep well last night, or that your stomach is bugging you, but the reason it's going to take an extra hour today is because Tim has a blister.
Whatever is holding up that server is what's holding up the entire train of communication. If that is where $5000 will fix the problem, don't talk about any other problems, you'll just confuse management.
The next place to stop if that doesn't work is, if you can't fix "Tim's foot" can you offload some things "he" is dealing with? Dump some of his load, work steal, etc. But these are just mitigations.
But this is the summary of a large part of that book: Systems have bottlenecks, address the bottleneck. Spending time on improvements elsewhere will not help the bottleneck, you're just wasting time/money. Data/material is going into it too fast to process (work is building up). Improving before the bottleneck just makes its queue fill faster. Improving after the bottleneck just creates a segment of the system that's starved for work. So focus on the problem at hand, once it's addressed, focus on the next bottleneck.
Buffering up does improve things when there is variability the processing time for each task, but it can also make average wait time hell. So you better be sure whether latency or throughput is really your primary concern.
I want to say no? If I were to reframe the question as a slow function that I had to call, I wouldn't call it IO bound, so I think not - the fact that there's IO in between the two components is more of a confounding factor in profiling than an actual performance limitation.
In short I think I/O bound is a concise way of saying that this work will leave my concern and will pass back into it at some later time.
Saying something is CPU bound means that the CPU is the bottleneck. For instance, the data IO doesn’t limit the system throughout of iteratively running a hash algorithm a million times, the CPU does. An IO bound process might be something like reading a lot of data off a disk (or over a network) with a small, quick transformation on the CPU. Where you saturate the data bus, but the CPU is comparatively idle.