RAM Usage for internet browsers

It's not unheard of.

Happens.

You shouldn't worry about them using what you perceive to be a large amount of RAM until it starts to become a problem. If it is slowing down your computer, not leaving enough RAM for other apps, etc. then you should look into the issue. Most apps today are built to automatically increase their share of RAM if it is available to make things run smoother, so if you have enough free RAM just sitting around then Chrome and Safari are going to start using it.

Virgule82 said:

Thanks for the replies, I asked because my computer was getting slow at 4 GB RAM. An upgrade to 8 GB should extend my iMac's lifespan by at least a year and I've been wanting to do that anyway. Seems 4 GB is really minimal for Lion....

Click to expand...

It is slow, because WebKit requires large amounts of RAM and virtual memory (swap). Even 8 GB RAM are not enough, if you use WebKit-based browsers in the background. My advice:
https://forums.macrumors.com/showthread.php?p=14989809#post14989809

Firefox + Adblock Plus + NoScript + DownThemAll is much better/faster compared to Safari.

They are simply using virtual memory as requested I suspect. If you run an identical version of Opera on a constrained device it will use a minimal amount of RAM. If you run the same rendering engine on a system with lots of free RAM, then it will use more RAM. The Opera browser is a great example of that, same rendering core from mobile phone up and code scaling as the OS allows greater allocation.

Chrome does use crazy amounts of RAM because of its process-per-page architecture, and I think is not a recommended browser if you open lots of pages simultaneously. Funnily enough Firefox (after years of criticism), is much more memory conservative than Chrome these days.