Your Mac is slower due to age and the v10.6 Snow Leopard operating system is way outdated. Apple has not provided security updates for v10.6 in several years.
One thing that can slow your Mac down is not enough available disk space.
Right or control click the Macintosh HD icon on your Desktop the click Get Info. In the Get Info panel you'll see: Capacity & Available
Make sure there's at least 15% free disk space.
If you haven't done so lately, check the startup disk for errors.
Launch Disk Utility located in HD > Applications > Utillities
Select the startup disk on the left then select the First Aid tab.
Click: Verify Disk (not Verify Disk Permissions)
If Disk Utility reports errors, restart the Mac while inserting the install disc and holding down the C key simultaneously. From there you should be able to repair the startup disk.