After noticing FF memory usage go up past 75 meg, I decided to trim down a lot of my plugins to the essentials that either save me bandwidth or one set of typing and clicks at least per session. I then started a series of comparisons with Opera. Most cases the comparison wasn't "fair" in that I compared types of use rather than actual page to page comparison.

First off, FF homepage (ABC news page) vs Opera Speed Dial (pretty sure it is default). FF = 32meg, Opera = 23meg. FF actually has to load up a site completely while Opera just uses cached images. To FF's credit, it actually does something useful for me in that I get some news that doesn't consume monthly quota thanks to Internode.

Where FF really falls over is when I start using stuff. Two tabs immediately make FF the worse browser, 45meg to 25meg. Over time, FF seems to be better at leaking memory as well.

All that said, FF is the browser that gets the most use. Firstly, it is because I have some nifty plugins I can't get to work in Opera, such as the Internode Games network tool. Second is a set of dynamic bookmarks which keeps my second row of bookmarks ranked by number of visits, thus keeping the useful ones up the top and the ones that aren't quite there near the top. Finally, I'm fairly strict with my settings in FF so nearly every page loads faster. This is probably because FF keep a Java whitelist and aggressive ad and flash blocking.

Basically what it comes down to is FF is the less efficient browser, but with my setup I have higher efficiency. Opera is the faster browser but a limited toolset. What this basically means is Opera is set as my default browser, so other apps will open windows in Opera and my speed dial is basically the list of things where Opera is "cheaper" for getting what I need. I'd probably use Opera more if I knew how to further optimise it for my needs, but I've hit my limit which has included writing a few libraries after reading guides. So in the end, it comes down to if I care about the extra RAM that FF is consuming and a majority of the time is that I don't when compared to the extra time it takes to use Opera.

Naturally, a big factor is how much RAM you have to begin with. if you've got heaps and aren't actually running out, the extra RAM usage doesn't make any real difference. Sadly, not the case for me.

Annoyingly, Opera is my "timewasting" browser, so I use it for stuff like LJ and gaming forums and stuff. When I do work, FF is faster, but it becomes when I'm doing big multitasking things. Having a dozen PDFs open, Word, EndNote, plus a statistics package means RAM does kinda become an issue. But given the power of FF, I've made the cuts elsewhere by running things like FoxIt Reader instead of Acrobat.

I wish it were the other way around, where the bloated FF was used for stuffing around and I used Opera for work stuff. What really confounds me is the general uselessness of so many of the widgets in Opera. Many of them I just have no need to use and I suspect many of them horribly bloat Opera too. Once I tried setting up the fish tank thing for a class of lower primary kids to do some money stuff and I had to scrap it because not only was it hogging RAM, it was using all the CPU cycles too.