Slow - upgrade to Yosemite

Question

My Macbook Air is starting to lag on simple tasks, like starting up safari. I don't have lots of apps either.

Answer 1

Try this.
Safari
  Go step by step by step and test.
1. Power off the router. Unplug it from the wall. Wait a while.
    Plug it back to the wall. Power the router on. Wait until all the lights are lit properly. It will take a while.
    Restart the computer.
    Start up in Safe Mode.
    http://support.apple.com/kb/PH14204
2. Delete Caches.db
    Close all windows and quit all applications.
    Hold "option" key down and click "Go" menu in the Finder menu bar.
    Select "Library" from the dropdown.
    Library > Caches > com.apple.Safari > Caches.db
    Right click the Caches.db file and select "Move To Trash.
    Close windows and relaunch Safari.
3. Empty Caches
    Safari > Preference > Advanced
    Checkmark the box for "Show Develop menu in menu bar".
    Develop menu will appear in the Safari menu bar.
    Click Develop and select "Empty Caches" from the dropdown.
4. Delete Cookies
    Safari > Preferences > Privacy > Cookies and other website data:
    Click “Remove All Website Data”.
5. Safari > Preferences > Extensions
    Turn off Extensions if any and launch Safari again to test.
    Turn on those one by one and test.
6. Deselect Proxies if selected.
    System Preference > Network > Advanced  > Proxies Tab
    Under "Select Protocol", uncheck any box if selected.
    Click "OK" then  "Apply”.