Steps to diagnose performance bottlenecks on Mac OS X

Found this great resource recently which details some more advanced dtrace-based commands which can be used to track down OS X performance issues; may be of use to people stumbling upon this question:

http://dtrace.org/blogs/brendan/2011/10/10/top-10-dtrace-scripts-for-mac-os-x/

I would begin with top (to see the process list at work). Take into account cpu usage / per process and memory usage. Followed by fs_usage (lets you monitor file system activity).

If your finding something using the disk often or using too much cpu your heading in the right direction. Also try vmstat 3; good for overall comparison of cpu, memory, disk (vmstat may be renamed vm_stat in newer versions of OSX).

Turn off every service you done need, is another good starting point. I would suggest you read man pages/howto's on these tools (there is too much to explain).

There is also the OSX activity monitor in applications/utilities which is much easier to read, but not so detailed as the utilities mentioned above.