Ibook G4 - runs slow

Question

Hi!  I am new to the community forums and I apologize in advance for my extreme ignorance!  Thank you to anyone who responds!  First things first, here is the information for my ibook G4:
Model Name:
iBook G4
  Model Identifier:
PowerBook6,7
  Processor Name:
PowerPC G4 (1.5)
  Processor Speed:
1.33 GHz
  Number Of CPUs:
1
  L2 Cache (per CPU):
512 KB
  Memory:
768 MB
  Bus Speed:
133 MHz
  Boot ROM Version:
4.9.3f0
Now, I do not pretend to know what any of that means, but I know it is useful info to help answer my question.  My G4 is running slowly, and it has been suggested to run Onyx.  I downloaded Onyx and when I tried to open it, I get the message "not supported by architecture".  Is there any help for this??  I know that I probably have a ton of junk floating around that needs to be cleaned up, but I am leery of any of the "mac cleaner" programs out there.  I am happy with my G4, but it would be great if it ran a little faster.  In addition, Safari seems to quit unexpectedly quite often and as far as viewing inbedded video, forget it!
I am runnung Mac OS X version 10.5.8.  Last thing - is there any version of Firefox that will work with this particular machine??
As I said, any help would be greatly appreciated and feel free to dumb down your responses - the simpler the language the better !!!
Cheers!
Bex

Answer 1

Did you download OnyX Version 2.0.6 for OS X 10.5? It's the third one on the download page, and that version will run on the PowerPC architecture.   Good practice says before using any disk cleaning software that you should have a backup of your system.