system.log, Safari, Mavericks

I've been having problems ever since I upgraded to Mavericks now running on OSX 10.9.2 on my iMac (mid 2010).
Today whilst checking system.log I found the following: -

local Safari[253]: CGContextSynchronize: invalid context 0x0. This is a serious error. This application, or a library it uses, is using an invalid context and is thereby contributing to an overall degradation of system stability and reliability. This notice is a courtesy: please fix this problem. It will become a fatal error in an upcoming update.

There is a long list and it involves these other contexts -
CGContextRestoreGState - CGContextTranslateCTM - CGContextSaveGState

I don't know what they mean and I don't know what I can do to fix the problem or whether to ignore it. But my mac is slow in opening applications like Safari or Mail and also microsoft office for mac. I have particular problems with adobe photoshop elements and sometimes iphoto.

Can anyone help?

Cheers

What are the specs of your machine? Since you're using a four year old machine, I suspect that's more the issue and not these rather unspecific errors.

Vansmith is probably right in what he says, did you perform a clean install of Mavericks originally, if not that can leave a lot of outdated data behind from your previous OS.
As regards the system log issue I have seen this before. Check Safari Preferences >Extensions get rid of anything outdated or just turn them all off and restart Safari see if that helps.

Thank you to van smith and Rod Sprague - I decided to use disk utility and repair disks, and things seem to have improved considerably. Irrespective of my iMac age, it has a new hard drive which was fitted curtesy of Apple in late 2012 and has followed all specified updates and upgrades. I'm not ready to chuck it out yet and do expect a mac to live up to its expectations for a few years. But will keep an eye on it. Cheers

OK, well glad you worked it out. I have to say I repair permissions and verify my hard drive a couple of times a year. Just repairing permissions can speed things up quite a bit especially if you use the computer daily like I do.