One of my hobbies since buying an 8-core Mac Pro is to actually make use of all of the processing power. So far I haven’t had much success. And, of course, the web and disk are not any faster, so the extra cores don’t do much good in general.
The only app I use that’s really built for that kind of thing is Xcode, which will spawn off separate compiler threads in parallel. However, I wasn’t seeing more the two cores busy when compiling a large project, though Xcode claimed to be working on 8 files at a time. I was thinking that disk or memory constraints were the problem, but it turned out to be a configuration issue.
At some point in the past, I had innocently turned on the Distributed Builds option, which is meant for distributing tasks to other machines on a local network. However, a side effect is that the compiling is throttled, presumably with thread priorities, so the build is more of a background activity. Turning off Distributed Builds gets all 8 local cores working in parallel.
Now I just need to get my own programs to use those cores…