What's a task-manager lighter than Activity-Monitor? [duplicate]

I’m a bit intrigued by the new detailed activity monitors and progress indicators in Windows 8 (copying files, the task monitor, network activity, etc.) It got me thinking: surely there must be some better alternatives to the built-in Activity Monitor.app?

“Better” as in more detailed and nicer graphs. Specifically, it would be interested and see percentage disk I/O (out of disk capacity), memory usage, and CPU usage in the same nice way as Windows 8 presents it.

The Building windows blog has an article detailing the new Task Manager in Windows 8.

I just think that OS X’s task manager — which I have always found superior — just doesn’t cut it anymore compared to what is coming in Windows 8.

iStat Menus and its free Dashboard widget version iStat Pro can show you a good broad overview of your Mac's systems, but I'm afraid I don't know of any monitoring utilities that show individual application processes (ie Finder activity copying files) other than shell tools like lsof or top.

edit I had forgotten about good old fseventer - last updated in 2010 but still working on 10.6.8.

Strictly for monitoring RAM use, FreeMemory works well. It sits in the menu bar.

I've been using MenuMeters for many revisions of OSX, it is similar to iStat Menus. I use it to keep an eye at real time performance like network and CPU.

atMonitor presents itself as “the most advanced monitoring tool for Mac OS X that displays system activity in real-time”, and is intended as an Activity Monitor replacement.