Macbook Pro Has Slowed All Of A Sudden

Question

Hello all..
I recently brought a Macbook Pro of eBay.
The machine was flying and I was more than satisfied with it.
I have just returned from working abroad to finding the Macbook Pro sluggish in its performance, very sluggish indeed giving the specs of it.
The specs:
Processor  2.7 GHz Intel Core i7 (W/ Turbo Boost)
Memory  16 GB 1600 MHz DDR3
Graphics  Intel HD Graphics 3000 512 MB
Software  OS X 10.9.4 (13E28)
1 TB HD & 1TB HD fitted into CD DRIVE.
At first I thought this sluggishness was due to it not being used for weeks, but then a thought don't be silly. I later noticed I had to hold the power button down longer than usual to boot it up.. Not the one tap and then bang! your good to go. I did install Mavericks OSX before I departed abroad, but had a good old play around and all was well.
What could be the problem?

Answer 1

Try these in order testing your system after each to see if it's back to normal:
1. a. Resetting your Mac's PRAM and NVRAM
    b. Intel-based Macs: Resetting the System Management Controller (SMC)
2. Restart the computer in Safe Mode, then restart again, normally. If this doesn't help, then:
     Boot to the Recovery HD: Restart the computer and after the chime press and hold down the
     COMMAND and R keys until the Utilities menu screen appears. Alternatively, restart the
     computer and after the chime press and hold down the OPTION key until the boot manager
     screen appears. Select the Recovery HD and click on the downward pointing arrow button.
3. Repair the Hard Drive and Permissions: Upon startup select Disk Utility from the Utilities menu. Repair the Hard Drive and Permissions as follows.
When the recovery menu appears select Disk Utility. After DU loads select your hard drive entry (mfgr.'s ID and drive size) from the the left side list.  In the DU status area you will see an entry for the S.M.A.R.T. status of the hard drive.  If it does not say "Verified" then the hard drive is failing or failed. (SMART status is not reported on external Firewire or USB drives.) If the drive is "Verified" then select your OS X volume from the list on the left (sub-entry below the drive entry,) click on the First Aid tab, then click on the Repair Disk button. If DU reports any errors that have been fixed, then re-run Repair Disk until no errors are reported. If no errors are reported click on the Repair Permissions button. Wait until the operation completes, then quit DU and return to the main menu. Select Restart from the Apple menu.
     Reinstall the 10.9.4 update: OS X Mavericks 10.9.4 Update (Combo).
4. Reinstall Lion/Mountain Lion, Mavericks: Reboot from the Recovery HD. Select Reinstall Lion/Mountain Lion, Mavericks from the Utilities menu, and click on the Continue button.
Note: You will need an active Internet connection. I suggest using Ethernet if possible because it is three times faster than wireless.
     Reinstall the 10.9.4 update: OS X Mavericks 10.9.4 Update (Combo).