Hi - If you think this may be more something to do with your system slowing down rather than the way you
compress clips or the speed of your external hard drive then these pointers may help.
I reckon you should be able to manage way more than 3 layers on a MacBook Pro with 1gb.
1/ Open the 'Disk Utility' application, select your system hard drive, select 'Repair Permissions', let it run.
If you regularly install and uninstall apps for instance, this may help, it's a bit of general housekeeping.
Some people swear by it, others don't think it helps.
I think it helps my system run better.
Also try App Delete
http://reggie.ashworth.googlepages.com/appdelete
or
App Trap
http://konstochvanligasaker.se/apptrap/
for completely deleting applications and all associated folders and files.
2/ Open the 'Terminal' application, when the blocky vertical black cursor appears type in
exactly the following text which I have shown here in bold:
sudo periodic daily weekly monthly
You will be prompted for you password.
Enter password.
If this is your first visit to Terminal there may be a dire warning.
Accept or decline as you feel comfortable.
Check you have the above typed in correctly, nothing more, nothing less, a few times before hitting enter.
(Beware that mistakes here can mess stuff up so do a back-up - you do back-up of course?)
Wait and wait, even though nothing much seems to be happening until the blocky vertical black cursor re-appears, this means you are done.
Don't noodle with the computer or click stuff until Terminal is ready, leave it alone and make tea.
This applies to most critical stuff.
Quit Terminal.
Your Mac is designed to do some automatic housekeeping every day, week and month at 3am in the morning or some such.
It's no big deal but if you never leave your machine on overnight then running this may help as it will run all the daily, weekly and monthly housekeeping that may not get done all at once.
Again some people swear by it, others don't think it helps.
I think it helps my system run better.
3/ Buy
Disk Warrior app.
I do swear by this. Totally worth the money.
Install as advised.
When things slow down, run Disk Warrior as advised, which for your system drive means booting from your dvd drive at a re-start or start-up.
There are full but ever so slightly confusing instructions with Disk Warrior. Read and follow them.
Also you might think of the following:
Set-up a Live Performance Network specifically for using when you perform.
Go to System Preferences then Network, then click on 'Location' and 'New Location' and give it a name, I call mine "Live Performance'.
Now for 'Live Performance' turn
off Bluetooth, Modem, Wireless & Ethernet etc etc so your system can concentrate during a gig, this can help hugely.
After a gig remember to apply the standard network or stuff like the internet may not work because something is turned off!
Remember to turn off the 'Auto Check for updates' option in all programmes. But you did that already right.
Make sure there is plenty of space on your system drive, it needs space to breathe.
Try 'What Size' to find out what is taking up all your space:
http://www.id-design.com/software/whatsize/
Hope some of that helps.
These are all things that work well for me.
if in doubt do some www'ing, there are lots of sites with more info on sudo periodic and repairing permissions.