This is one of the most common reasons for browser slow-down. There are some good tools to detect and get rid of this on your PC, and they are free to download. Here are some of the applications which are commonly used:
Hijack This – This program scans your PC and logs all processes running on your machine. You can have a look at the log and determine if there is an unknown process running, or post the log on a forum (such as http://www.pchelpforum.com/) where they can help you determine the status of your computer. Processes which normally should be running are your ‘iexplorer.exe’, your ‘svchost.exe’ processes and other programs which you have installed. However, some spyware can mask as a legitimate process, hence why it is helpful to seek advice when looking at the program’s log.
Ad-Aware – A very useful program, which offers a free version and a priced one which comes with more features. The free version, however, is perfectly usable and can help in seeking and eliminating threats. The program runs a scan, which can be a quick-scan or a more in-depth one, in order to determine threats which affect your computer. You can then tick boxes which will remove the risks displayed, which can be either cookies or crawl-bots or other forms of spy/adware.
Spybot – As well as scanning your computer for malicious software, it can run in the background to protect your browser from unwanted cookies or spyware. The company also offers other related solutions, such as a registry analyzer or a program which allows you to edit Windows services, stopping any hidden malware.