Blizzard has made a large programmable environment and hundreds of modders are making useful mods in it. Yet there is very little support inside the game for debugging, profiling, tracking and so forth. There are some useful add-ons which can help you in making your own add-ons or with checking what is going on in your client. I have found them extremely useful when checking memory requirements of my add-on collection in addition to trying to figure out which add-on was using most of my processing power.