Ok, I am using Debian and when I was playing some games and viewing videos (anything that requires Adobe Flash Player) after a while, I started to notice my computer slowing and slowing down. So I closed Iceweasel (Firefox) but the absurd RAM consumption still persisted. I have some widgets on my desktop displaying the RAM and SWAP Consumption. RAM was almost full, only had 200 MB left (I have 2 GB) and the SWAP as almost full. I had to restart the computer, since the "ps aux | grep iceweasel" wouldn't show me anything. After a brief search on the Internet I found a solution for it (well, it's not really a solution, it will just limit the RAM resources)

In Iceweasel, go to

In the filter field, search for
Now set the value to true if it was false.

Now, create a new string value by right clicking.
On preference name type:
After you type the preference name, it will prompt another window for you to input a value. That value is for the memory cache and it is in KB.
So, now enter the value of Memory cache in KB.

• 512MB of RAM --> 8192
  
• 1GB of RAM --> 16384
  
• 2GB of RAM --> 32768
  

Very nice fix! Hopefully this will help anyone using IceWeasel. I am guessing there is a memory leak in the Flash Player plugin.

Iceweasel would always crash for me however firefox wouldn't, I prefer Chromium since everything works just fine on there.