Main HDD Diagnostic Thread

I would like to propose this as a main thread for all questions regarding HDD/SSD problems.
Speaking of which, I have a problem of my own to ask.

I have a WD5001AALS-00L3B2 HDD and in the past I had a fake sector (a sector wrongly marked as bad) that whenever the OS/user tried to access that portion, the HDD would fail, rendering the entire system useless unless a restart was performed.
Now, that sector was corrected. No errors of any kind in HDtune or HDD internal SMART but something is tied to that little experience. Even though there are no errors I get the following benchmark:
Attachment 14016

I don't think this is normal. And it wasn't like that before that event occured.
Ever since my HDD is very slow in games and other applications.

In starcraft 2 heart of the swarm, it takes me 2 minutes to load a mission. Sometimes longer.
Same thing in Skyrim, 1 minute to enter in Whiterun and 2 or more minutes to switch from outside to inside (city to house, for instance).

I'm so sick of this. I should know better but I can't find the reason.
How to debug something that doesn't give an error?

Code:

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HD Tune Pro: WDC WD5001AALS-00L3B2 Health

ID                                  Current  Worst    ThresholdData    Status 
(01) Raw Read Error Rate            200      200      51      193      ok     
(03) Spin Up Time                  167      164      21      4641    ok     
(04) Start/Stop Count              98      98      0        2112    ok     
(05) Reallocated Sector Count      200      200      140      0        ok     
(07) Seek Error Rate                100      253      0        0        ok     
(09) Power On Hours Count          83      83      0        12949    ok     
(0A) Spin Retry Count              100      100      0        0        ok     
(0B) Calibration Retry Count        100      100      0        0        ok     
(0C) Power Cycle Count              99      99      0        1977    ok     
(C0) Unsafe Shutdown Count          200      200      0        400      ok     
(C1) Load Cycle Count              200      200      0        2112    ok     
(C2) Temperature                    116      98      0        31      ok     
(C4) Reallocated Event Count        200      200      0        0        ok     
(C5) Current Pending Sector        200      200      0        0        ok     
(C6) Offline Uncorrectable          200      200      0        0        ok     
(C7) Ultra DMA CRC Error Count      200      200      0        0        ok     
(C8) Write Error Rate              200      200      0        0        ok     

Health Status        : ok

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Thanks for the help. Hope I don't offend anyone/break rules of SB-I by creating these main threads.

How exactly did you "correct" this bad sector? Speaking from my own experience, when I had bad sector it was fine for a while but then my HDD just crashed and died.

The problem appeared in December, 2012. The error was marked as Current Pending Sector in HDTune and the only way to correct it was to scan the entire drive with WD DLG. After it finished there was no fake sector.
Stats were clean.

It was enough to just scan it for errors. Correcting it resulted in other errors as DLG wanted to mark it as a bad sector but it couldn't.