Chosen Solution

I’ve got the uni body mid 2012 macbook pro and wanted to improve the speed. I’ve replaced the optical drive with an 1TB SSD and I’ve switched out the RAM so it’s now 16GB But it still feels a bit slow What am I doing wrong… Or Rather what haven’t I done. I’ve read up and apparently it’s better to install the OS onto the SSD, but is that still possible when the SSD is already in the mac and if so how can I do it and how do i keep all my stuff?

From my experience there is a world of difference when you run the OS on an SSD rather than a regular spinning hard drive.  I am not quite sure how Mac OS do it but there should be a way to migrate your OS over to another storage device.  If I were you I would recommend just googling “Migrate [or Copy] Mac OS to separate device” for instructions on that part since Mac OS might have a simple way of doing it.  The other bit of advice ill give you is that a computer back in 2012 is probably a bit dated by now, especially the CPU (8 years old now if never changed), so a new CPU would improve your device performance noticeably.  Other than that your laptop could be over heating which sometimes leads the computer to slow down performance in order to not overheat and damage itself.  Hope this helps.