Linux uses a Buffer and a Cache in the RAM. The way I understand it (someone can correct me if I'm wrong), the Cache loads loads the last files that were in use for faster access, and the Buffer loads the current file in use. If it needs more RAM, it will clear away some of the Buffer and Cache to make room for the needed RAM-clearing away all of the Bugger and Cache if needed (though this is very rare that it "needs" to clear all the available RAM).

Thanks for all the responses!

That link was helpful. It (and H_TeXMeX_H) suggested checking free... so here's the output of free -m:
I should note:

• things are not particularly bad at the moment - but when I accidentally right clicked on a popout Youtube video in Firefox, and then left-clicked the play button, things froze for about 20 seconds.
• My swappiness is drastically reduced, to about 5 or 10 (can't recall). When I changed this, I don't recall a big change.
• I have a habit of running a lot of programs at once, and having a lot of tabs open in Firefox and Opera. (My record is about 120, but I'm keeping the number down these days.)

czarr:
I don't know, but it certainly seems to.

More shortly...

I'll try Xfce. Though I like GNOME, I don't recall XFCE being hugely difficult. I was using Xubuntu 7.04, which I found very buggy and unstable on my machine, but in hindsight that was probably Ubuntu more than Xfce (as Ubuntu 7.10 also didn't work well for me).

So, I want distro with Xfce and installs from LiveCD (important for ICT4D - a LiveDVD like OpenSUSE is a bigger demand on resources, needing bandwidth and newer hardware.) It seems that OpenSUSE is easy to use, so I hope they do an Xfce LiveCD soon. Xubuntu gave me grief before, which seems to leave Fedora - so I'll get the Fedora 9 Xfce spin when it comes out in mid-May.

But does Fedora have an equivalent of PLF to easily get the latest "non-free" codecs etc?
did

I did the test at zegenie Studios and told it I had an old machine (so it would give me fast distros). It suggested Fedora & OpenSUSE. Others (Mandriva, Ubuntu, Kubuntu & Debian*) listed lower becaule "Your computer may be too slow". Is this saying that Fedora & OpenSUSE are faster than those other distros even if using the same desktop? This doesn't quite make sense to me, as I thought Debian was supposed to be very fast.

Thanks again for the help

* Debian also doesn't have a a graphical installer - again not one to share with newbies - plus I get the feeling that ideology sometimes wins at the expense of usability.

I think you have something very strange going on here!

I'm using Fedora 8 with Gnome on a five-year-old machine (AMD Sempron 2600+, 500MB RAM). As a test, as well as reading this page in Firefox, I've loaded OO Writer with a 50,000 word document, Gimp with a JPEG, and the System Monitor. The result is 215MiB memory use and CUP loading < 60%. So where's your 400MB going?

The only thing that taxes the CPU is Bluefish, the only thing that exhausts the memory is Fontforge editing Code2000.

I have found Fedora and Suse to be a lot slower than Debian or Ubuntu. Two things that you'd better get rid of if you use Ubuntu (or any other Linux for that matter) are tracker and maybe beagle. Beagle is not as resource intensive as the other one but why let it suck up resources when you don't need it? Firefox 2 is another renowned resource glutton - firefox 3 is a lot better in than respect. Unlike firefox 2, it restores resources that are freed when a tab is closed. But bear in mind that each new tab still sucks up extra resources. Flash - that is an absolute disaster and possibly one of the poorest applications around.

And Debian does have a graphical installer, only you may need to select that option yourself.

I find Ark Linux with Fluxbox installed from the repos to be very fast, though if you have at least 256MB RAM, then the default KDE will do you just fine on Ark.