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I have a mid-2009 MacBook Pro 15. When it wouldn’t boot properly, diagnostics told me there were S.M.A.R.T. errors affecting the hard drive. I replaced the it with a new (Toshiba L200) hard drive–a larger one, 1 TB. After finally booting the laptop using my external hard drive (MyBook), I installed OSX Mavericks from the internet. I then used an old backup from that external drive, transferring everything from my most recent backup in 2014. Then I noticed that iTunes was very slow/unresponsive at certain moments (like freezing when I would try to scroll down with the trackpad. There was a lag when in FireFox sometimes, as well. In the App Store, the newest OSX update is not compatible, apparently. When I first ordered this laptop, I paid extra for the most possible RAM. I know the RAM should handle whatever I may be doing. Yet I’m not sure what I can do to speed this thing up. There is so much free space on the hard drive. Does anyone have any feedback for me on this? I’m in uncharted waters. Thanks!
I’m less concerned with the your choice of drive. You have a SATA II (3.0 Gb/s) system so the drive you put in needs to support this older spec. This drive does, its fine! One of the issues the unibody system have is SATA cable breakdown. A slow system could be a worn cable. Here is the IFIXIT guide to replace it: MacBook Pro 15" Unibody Mid 2009 Hard Drive Cable Replacement and here is the part you’ll need: MacBook Pro 15" Unibody (Mid 2009 to Late 2011) Hard Drive Cable - Apple P/N 922-9751. To help prevent this from happening again place some electricians tape under the cable where it rubs against the upper case. You’ll also want to check the plastic bottom cover tabs are not broken. Make sure the one nearest the cable is in good shape. What can happen is the cover can flex damaging the cable. I add some stiff foam tape on each side of the cable to protect it as it crosses the edge of the optical drive. Sadly, you’ll want to reformat the drive and re-install the OS and your data. As the drives structure is likely damaged from the bad cable. You may also want to up the RAM to the max this system supports (8 GB) if you haven’t already.
Toshiba L200 is an 5400r with 8M hard disk. It’s actually not that good and it’s cheap . If your origin hard disk is high-quality or even an SSD, this situation is actually simple. By the way, your computer is an 2014 model, it’s not a new one, it’s simple for it to work little bit slow, actually.