Growl is a notification add-on, lets you know when something is updated or changed.
DivX is nothing but a Video codex, still used by PC users (obsolete IMHO) but works on Mac as well if you have installed Perian, which gives you additional codecs for QuickTime. Just having video in DivX is irrelevant to your problem.
iCloud is turned on/off in your System Preferences.
Activity Monitor lets you look at lots of things happening on your Mac, any of which could be causing your delays or slowdowns.
CPU will show how the multiple processors are being utilised. If they max out something is taking all your processing. Each process is detailed in the list.
System Memory shows if all your RAM (electronic memory) is being used. If 100% is used it starts using your Hard Drive. Having lots of Tabs open in Safari particularly eats up RAM. I installed 12GB on my Mac which practically eliminates this but I still sometimes top out.
Disk Activity shows how your Hard Drive or USB devices are being used. This is much slower than RAM and may have a delay as it spins up. "Green" hard drives are a particular problem as they actually stop spinning to save energy. Newer "Red" drives from Western Digital actually do a far better job of saving energy without the delay.
Disk Usage shows how much of your drives is being occupied. OSX writes a lot of stuff to "Swap spaces" on the Hard Drive when it doesn't get to hold it in RAM. OSX likes at least 10% for swap, 20% is better.
Network monitors remote traffic, which can be caused by you saving or reading from a server, either local or remote like iCloud. This is the slowest of all activity on your computer, very very slow by comparison with everything else. Some software writes or sends notifications "Back home" to the publishers's website. Adobe is one offender as is Hewlett Packard's printer monitoring software. Little Snitch can monitor and prevent this and is a great method of protecting your Mac from intruders as well.
Another possibility is your Optical Drive, if you have one. Should you have a CD/DVD in the drive this can interrupt if it is being read or written to. Same with USB flash keys, which are usually in FAT32 (Windows) format.
Spotlight can take resources as well if it is indexing your Hard Drive/s.
Lastly do you have Boot Camp running Windows? This uses lots of resources of all descriptions.
Many users seem to think computers will endlessly take anything you throw at them. Not true, they all have limited resources which can be taxed, if you push them hard enough.
Peter