here's some of my tips!
1st there might be some registry errors or unwanted in your system
which may causes high memory usage.
2nd you might have open to many program's at once, desktop
wallpapers may also affect memory usage, if there are more
program's running all at once each of its program memory usage will
also increase this is what i experience in many computer's i have
used.
my firefox has 55k memory usage.
actually if you plan to have a fast pc is best you get a good
processor, maybe 1gb of ram and better motherboard?? mine is 3gb
ram.
graphic card may also come to play apart with memory usage, if your
window is like enhanced with lots of widget or very high resolution
desktop wallpapers may also effect slowing down yr pc. and since
your pc is like taken alot of memory opening up programs with about
40k memory usage will of course slow down yr pc even further.
the pictures and words on webpages also play apart!
virus's also play apart
you can try some my method to improve your pc speed.
1st go to start - control panel - display then you can change a
different desktop wallpaper with lesser resolution and not so
colorful
2nd method - start - control panel - display - setting change
resolution will help.
3rd method - start - all programs - accessories - ssytem tools -
disk defragmenter, this can be quite long and if u recieve error
its time you get yr pc for repair, it means yr system files might
have been corrupted or virus attacks i'm not to sure on this no
confident.
because color has binary number which are called hexidecimals 1 - F
so displaying colorful wallpapers, the system will have to go pass
many logic gates from the processor and to display your colorful
pictures that will have alot of hexidecimals.
theres are alot more advance techniques but i'm still a beginner
and hope to learn more.