Having what appears to be memory problems when using Firefox on
my Slackware 12.0 system. Certain web sites with lots of graphics
such as news and movie sites take a long time to load and then
stop and hang. Commensurate with the hang is a lot of disk
activity as if RAM is being offloaded to swap. However it never
completes.

I have been using Firefox 3.0.1 and have changed back to the
2.0.0.4 version supplied with Slackware 12.0 after reading that
Firefox 3.0 is a memory hog. Unfortunately, the problem persists.

While my 256K of RAM is not large by today's standards, it has always
been sufficient. In fact, the Windows version of Firefox (v 2.0.0.17)
has no trouble loading the aforementioned web pages completely on
a Win98SE system on the same machine.

I have also tried the SeaMonkey browser included with Slack 12 with
the same result.

I suppose I could have picked up a virus or some sort of malware but
have no way of determining what the problem is on my system. There
also may be a problem with virtual memory.

Can anyone suggest how I might approach a solution to this problem?

What plugins are you using for FF under Linux ? Anything to view movies ?

Only plugin is Flash 9

Did you try to clear the firefox cache (edit > preferences > advanced)
Maybe a profile problem ?
mv ~/.mozilla ~/.mozilla.bak
mv ~/.firefox ~/.firefox.bak
firefox &

FF3.* uses less memory than FF2.*...
How is Konqueror behaving?

Clearing cache helped a little; at least the page loads completely,
but disk thrashing still occurring. Pretty sure not a profile problem.
Even though page loads completely, further navigation very slow and
disk thrashing intensifies even if I am just closing the browser.

It's surprising that FF2 would be more of a memory hog than FF3.
Konqueror and SeaMonkey exhibit similar slowness.

It appears that the only solution is more RAM, unless there are
any other ideas?

Could you post output with: free -m and df -h ?

How much RAM do you have?

Edit:
sorry, hadn't read keefaz' reply.

256K RAM

free-m
df -h

You don't have a swap partition?
Probably that's the reason of the slow response.
You might add some extra RAM, but I think the lack of swap (with this amount of RAM) is the culprit.

Yes, you need a swap partition, say a 500-700MB partition for swap
BTW you have 256M of ram memory not 256k(!)

I'll wager /dev/hda2 is swap.

Yea, sorry, it's 256M RAM and 900M swap.

Trouble affects both FF and SeaMonkey even after
cache is cleared in both (i.e. both browsers are
now choking and hanging on graphics heavy web pages)

Tried to do a free -m after web page loaded but could
not get it to load completely again.

Hang occurs as status bar indicates either:

"transferring data from www......" or

"waiting for data from www......."

Activity indicator and progress bars just freeze.

Then how do you explain this:

Your swap partition is obviously not active. You should format the partition with mkswap, if necessary, and then activate it with swapon (both as root). There should be a line like the following in your /etc/fstab (assuming your swap partition is /dev/hda2):