There is no speeding up software for Macs that I am aware of. My Mac is early 2007 and it is fine. Every program you run slows down the computer a bit. If you are running the dashboard that slows it down. Some programs slow it down a lot. You may have a program that is really screwing it up. I am not sure what you can do about that.
Do you have all the updates for your OS? Go to 'Apple' (top left corner of the screen) 'System Preferences', 'Software Update' (4 down 4 across) click on that and it will run automatically.
What OS are you running?
I use two programs for fixing the Mac and both are payware -
Disc Warrior
http://www.alsoft.com/diskwarrior/TechTool Pro
http://www.micromat.com/techtool-pro-6-learn-moreI run these monthly and have it in my schedule to remind me.
The other thing you can do is to get out the 'Techtool' version that probably came with your computer and try that.
One easy thing to start with is to turn off the Mac, unplug it, then if it's a laptop, turn it over, remove the battery, or if it's a desktop, remove the plug wire from the unit. Not just from the wall. Leave this off for say 2 minutes. Then plug it all back in again. This resets something inside.
Also run Disc Utility.
Select 'Finder' then select 'applications' then select (almost the bottom of the list) 'Utilities' then select 'Disc Utility'. When that opens up you click on the left where it says 'Macintosh HD', then select 'Repair Disc Permissions'. Run that a few times. Don't ask why it doesn't repair them all at once. God only knows why...
Each time will take 5 minutes or less.
BTW it doesn't hurt to run this say once every month or two.
Then after that, click on the left side where it says the size of your HD (Right above MacIntosh HD) Mine is 250 GB, Then go to the right side of the box and click on 'repair disc'. Run that once or twice.
See if that helps.
I will post how to do the next step after I try it first, as I don't have it memorized.
It involves using the Install discs, so go find them.
BTW you might try Googling your question also.