If your PC has slowed to a crawl, it's hard to tell how many other types of Malware could have been injected into your OS. Generally, malware has a nasty habit of putting even more malware on your PC. I don't know which AV/Malware scanners you have but here are some suggestions.
Since your PC may have multiple malware processes running based on the fact it's very slow, in this instance run RKill before scanning & do NOT reboot. Once it's run, start scanning with your malware scanners.
Malwarebytes, the free version will work fine. D/L & do a full system scan, quarantine anything it finds. It will offer you the option at the end of the installation to start a free pro version trial for 14 days. You can uncheck this or leave it checked as Malwarebytes has made it easier to opt out of the trial.
As RKill only terminates a program's running process, and does not delete any files, after running it you should not reboot your computer as any malware processes that are configured to start automatically will just be started again
. Instead, after running RKill you should immediately scan your computer using some sort of anti-malware or anti-virus program so that the infections can be properly removed.
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And just to rule out the possibility of a rootkit, run TDSSKiller.
TDSSKiller is a utility created by Kaspersky Labs that is designed to remove the TDSS rootkit. This rootkit is know under other names such as Rootkit.Win32.TDSS, Tidserv, TDSServ, and Alureon. TDSSKiller will also attempt to remove other rootkits such as the ZeroAccess or ZeroAccess rootkit if it is detected.
When running TDSSKiller, launch the program, click on the blue text "Change Parameters" & check the box marked "Detect TDLFS File system." Click OK & then run the scan.
You also have the option of doing a system restore before the point of the infection. If this is possible & you want to pursue that course of action, be sure to roll back 2 or 3 points past the infection point as some malware embeds itself in the 1st restore point to keep from being deleted.