newbie with a problem..

[verymeta at riseup.net]

Hi all. I'm very much a newbie, and I've been making music on Ubuntu for a
couple months now, even though I don't know as much about Linux as I
probably should. My usual setup is to have up to 8 or 9 amSynths,
sequenced in Seq24, and maybe Creox for special effects, running on Jack.
Up until recently I couldn't get amSynth to work in real time so I just
ran it not in real time and put up with the clicks and static.

Finally I got tired of this, reinstalled Ubuntu and got Jack and amSynth
working together in real time (it took me a day and a half, but I managed
it!) Now the sound quality is beautiful... if I only open 4 or 5 instances
of amSynth. But if I open more than that, my laptop makes a horrible noise
and freezes, and the only way I can shut it off is to take the battery
out.

I spent some time trying to figure out why this happens and finally
twigged that the Jack panel shows its CPU usage. When I play just one
amSynth the CPU usage is 41%, and for 5 amSynths it's a massive 82%, which
explains why my computer freezes. So it seems my computer just isn't fast
enough to do what I want it to do :-(  So my questions is, is there
anything I can do to fix this, short of buying a faster computer? Would it
help if I got a better soundcard? I don't mind spending some money to fix
this if I have to, though obviously I'd rather get the computer I already
have to work if possible. My laptop is an IBM Thinkpad T40, 1.50 GHz, and
the soundcard is a Radeon Mobility 7500.

Any suggestions gratefully appreciated,
Katie.