There can be a variety of problems that can slow a machine down. If the performance is poor in only one program, the first approach would be to delete and reinstall that program. For slowness across all programs and OSX, here is a list of things to check.
Back up now: The first thing that I will say before attempting any repair is to make sure you have a complete and up-to-date backup of all of your data. Do a backup now if you haven’t got one.
Not enough RAM: First off, how much RAM do you have? 4 GB is the practical minimum for Intel Macs, 2 GB or the model maximum is desirable for PowerPC G5 and G4 machines and first generation Intel CoreDuo Macs. Most modern Macs can go to 8 or 16 GB of RAM, and that is the most cost effective way to speed up a machine.
The more multi-tasking you do, the more RAM you need. When your programs and data use more memory than you have RAM chips for, OSX is forced to swap memory contents on and off the hard drive, which causes a slow-down.
If you are using Photoshop or professional level graphics. photography, animation, video production, audio production or engineering software, add as much RAM as you can afford. Order Macintosh RAM here.
Multitasking overload: How many programs do you have running in the background?
Hint – when you click the red button at the top of a window to close it, you are not actually closing the software program, only that window, and the program remains running in the background. You need to go to the top menu bar and actually Quit the program, or right-click (or option-Click) on the program’s icon on the Dock.
You can go into Activity Monitor and check what programs and processes are running, and see which are consuming RAM and processor power. Sometimes software has “memory leaks” which gradually lead to the piece of software using more and more memory and CPU. Examples Safari 6 with AdBlock or a third party sceensaver. Make sure your software is all upgraded to the latest versions.
Full Drive: How full is your hard drive? If the drive is over 75% full, then you are operating on the slowest tracks on the disk. Drive speed falls by about 50% from the outer tracks (fastest) to the inner tracks. When you hit 90% full you can run into real slow downs. If you are chronically out of space on the drive, consider a larger, faster new drive. You can use a utility like WhatSize to find out which files are using the most space on the drive, and a program like OnyX to delete caches and temporary files (careful with OnyX, don’t do anything that you don’t understand).
Dying drive: Extremely slow performance in the Finder and all programs can be the sign of a failing hard drive. If your machine is under warranty, take it to an Apple store or an authorized service center to have it checked out, or take it to a competent Mac tech.
USB: Occasionally, slowness can also be a problem with a misbehaving USB peripheral. Unplug everything except the keyboard and mouse.
Repair Permissions: A preventative maintenance item is to run a Repair Permissions from Disk Utility (Applications: Utilities: Disk Utility). Do this especially after installing new software or importing a lot of files. It is unlikely to solve a speed problem on its own, but it is one checklist item. http://support.apple.com/kb/HT1452
Disk Repair (Safe Mode): Another technique is to start the machine up and hold the Shift key down through the startup, you can release it when you see a progress ‘thermometer’ bar on the screen. Your machine will take several minutes to start, and during this time it will perform some self diagnostics and repair on the data structures of the hard drive. When it has finished starting up into Safe mode, you can restart the machine again and log in as normal.
Corrupted Software: One cause of slow performance is software that is either damaged or is hogging the machine’s resources. This includes the various services and helper applications that start up when you boot, and it can also be damaged Preference files in the user account.
Try this: in System Preferences, Accounts, create a new user and give it Admin privileges. (you need to click the lock icon and enter your password before the + icon for adding a new user becomes active) http://support.apple.com/kb/VI32
Now, reboot the machine and log in as your new user.
Is the machine faster now? Then your problem is some software that you have loading in your main account. You need to look through your Account’s Login Items, and perhaps clean out some data files and Preference files. If it is the same speed with a fresh User, then it is either a hardware problem or an operating system problem.
More troubleshooting steps:
Repair Disk routine: With your OSX DVD in the optical drive,
- Restart the machine and hold down the C key as it boots. it will boot into the Installer from the DVD. Answer the language selection but go no further.
- Go to the Utilities menu at the top and choose Disk Utility.
- Choose your Macintosh HD (or whatever your main hard drive is named)
- Choose Repair Disk, and let it run.
What are the results?
Is the S.M.A.R.T. status of the hard drive OK or FAILING? If it reported that it was unable to fix a problem, then the hard drive is either failing, or the catalogs of the hard drive are damaged badly. Consider taking the machine to a competent Mac tech at this point rather then continuing. http://support.apple.com/kb/PH4406
Reinstall OSX: You can reinstall the operating system without damaging your data: If the hard drive checks out OK, then proceed into the Installer, and do an Install (NOT an Erase and Install) of the OSX. On OSX 10.6 and later, this will reinstall the OS but leave your accounts, data and programs in place. (In OSX 10.5 and earlier, choose the Archive and Install option to preserve the data http://support.apple.com/kb/HT1710)
Then you need to do another round of Software Updates immediately
Is it faster now? If so then it was an issue with OSX.
If not, things are looking more like a hardware problem.
Check RAM and cable connections: Shut the machine down all the way, unplug it, and remove and reinstall the RAM memory modules. On a MacPro or a PowerMac you can also unplug and reseat the internal cables and PCI-e cards, (other Macs are not accessible). Restart the machine and check that all of the RAM modules are registering in Apple Menu, About this Mac, More Info, Hardware, Memory.
Hardware Test: Your machine’s bundled DVD may have Apple Hardware Test on it – if so the instructions how to enter AHT will be printed on the face of the DVD. Run AHT and see if that gives any information. http://support.apple.com/kb/HT1509 Consult with a tech.