Have you tried the basic troubleshooting things like emptying the caches and resetting the PRAM? Try this; restart, immediately after the chime, press "command + option + P + R" and wait until you hear the startup chime again, it should take less than one minute. This will clear out a lot of old cache data that may be making your system run slowly. Also, you're using an out of date OS, it doesn't have the best security for you, if you are using this computer for work and can't update to a newer OS, I would highly recommend using this computer for your work assignments ONLY and another computer for browsing the web and trying out new programs. If this doesn't work, then I would back up the entire hard drive (if its for work you should have it backing up daily), ERASE the entire thing and then start building it up again, this will erase any malware that you have on it. Macs are wonderful for not getting bugs and most malware is written for Windows, but more and more we are seeing bugs that attack Macs, most likely phishing bots and other nasties that steal your information. Also, when browsing the web, use a VPN if possible (Virtual Private Network) If you download and install the Opera web browser (which is optimized for OSX), it comes with a free VPN I've had no trouble with so far. Also, go into your system preferences, open Users and Groups, and open 'login items', turn off whatever you aren't using. I would also look up 'keeping your mac running smoothly' and read a few articles before erasing your entire drive, but that is the only way to make sure to get them all. Hope this helps.
