Is there a GUI app on Mac similar to Task Manager on Windows? My MBP is running slow this morning and I would like to see what it's doing. I know I can open a terminal and run 'ps' and 'top', but what can I use from the desktop?
Activity Monitor is the graphical application that comes with every OS X install for viewing and managing processes from your desktop.
You'll find it under Applications -> Utilities in a default OS X install.
In order to manage all the processes displayed in Activity Monitor you'll need an account with administrator privileges on the machine. With a lower privilege account you can only only manipulate your own processes or processes from groups to which you belong.
Here's a quick summary of the kinds of thinks you can accomplish with Activity Monitory. And a guide for finding out what's keeping your machine busy.
In particular, if you suspect you're running slow because of applications using excessive CPU, you'll want to click on the 'CPU' column header to sort applications by their CPU use. If you spot a few applications running hot you can use the search box to limit the Activity Monitor view to just a few applications.
The spinbox to the left of the search box contains some different view filters that can be handy. In particular I find the 'All Processes, Hierarchically' view to be valuable when it comes to tracing down parent processes of rogue child processes so you can see where things are coming from. It's a bit like pstree but interactive and continually updating.