Reverting back to factory state is NOT the best solution in your case. It's NEVER a good solution and should ONLY be reserved to absolutely desperate cases when nothing else works.
In most cases, it's like swating a moskito with a nuke.
Restoring to factory settings also reinstall all sort of mostly useless junk that was preinstalled and that you removed. Worst yet, those preinstalled programms are now obsolete and WILL STRONGLY degrade your performances.
First thing to do is remove as many startup items as possible. First to remove are any preloaders. All those so called "quick start"... They DON'T work and do make the whole system slower. Well, they may work, but only if you start the associated application within about 10 minutes after your started the computer. After that time of after you started some other application, they get pushed to the page file where thay no longer offer any benefit.
Make a list of the installed applications and uninstall those that you no longer need.
Clean out un-needed files like temporary files, old update uninstall files and such. Periodicaly empty the trash.
I regularly use Ccleaner from Pyriform. It does a excelent job of cleaning all sort of old un-used files and junk. FREE for personnal use.
DEFRAGMENT your drive! A fragmented drive can bring your computer to a crawl when opening applications and documents. It will also slow down the saving of your documents.
This must be done at LEAST monthly. A weekly defragment is recomended.
The stock Windows provided defragmenter is not effecient. I recommend using Defraggler from Pyriform. It's FREE for personnal, domestic use.
If you have an SSD drive, you MUST NOT defragment it. It's a special case.
If you have more than one drive, and almost anybody should, relocate the virtual memory to the second drive and give it a static size. A static size means that it won't get fragmented. A fragmented page.sys file will heavily degrade your performances.
If it's a new drive, you should place the page file there FIRST before you put anything else on it.
To manage the page file or virtual memory, open the controll pannel and the System applet.
Sellect the "Advanced" tab and click the Parameters button for the Performances section.
Chose the Advanced tab and click the Modify button.
Sellect the second drive and chose "personalised"
For "initial size" you enter a value of 3x your RAM amount.
Enter the SAME value for "Maximum size".
Click the "Define" button.
Sellect the drive/partition holding Windows and sellect "No page file" and click Define.
Click OK to close evrything and reboot the computer.
If you have only one drive, don't relocate the page file. Instead, make it a fixed size at it's actual location. At least, it will prevent it from been fragmented over time.