The reason your computer works so slow is because that on startup, the Windows pop-up advertising and spam acts almost like a virus that anti-viruses do nothing about because it is not a virus but it is annoying.
In this article I will recommend a useful program which which is absolutely free with an option to donate that might help your computer work a little faster.
Download: GoGoData.com.
Please make sure that all internet browsers are closed. This program will close all the open browsers automatically.
Step 1:
Click on the link and save the file to a place where you can find it such as desktop/my documents/C:/ / D:/ or any driver you have. Next open the file, the file looks like this:

Step 2:
Click on the file and press enter, then a window will pop-up. Click next the window looks like:

Step 3
The next window looks like this: Click next once again:

Step 4
The next window looks like this. Click on Agree

Step 5
A new window will pop-out like this: and will tell you that it has to close all the other browsers except the installer click ok.

Step 6
Now you have to choose where to install the program that looks like this: Select a place on your computer to install the program. (I recommend on the most space hard disk).

Step 7
Install and press finish:

Step 8
Now you have a new Auto pop-up/spam advertise blocker! Now log into the program.

Step 9
In the new window, there will be visible programs that run on startup. Watch carefully and mark the items that you do not want to start themselves, but be very careful! You could accidentally mark items that are important for the Windows! If you want to make sure, type in the section below the name of the program and press search the web and double check! It should look like this:
Step 10
Once you have blocked the programs you wanted to block make certain that they are not needed for Windows to start up. If you are unsure and have possibly blocked a program that you want to be running for any reason, then do the same thing….right click and “startup control (windows)” and then choose restore blocked programs(s) to auto-run at windows startup” then a new window will pop-out and you will have to mark what you would like to be unblocked.

Step 11
There is another option which is called history cleaner that will clean up all the unused internet cookies automatically. The way to use it is to press right on the program and then choose “Run History Cleaner(please close all open browsers before using)” then just click on it and its will clean it example:

Finally, you can restart your computer and feel it speeding up a bit.
Have fun!