Spybot Search & Destroy
Alas, Spybot Search & Destroy has served us all well at blocking and removing malware. It has come to pass that it is not compatible with IE8 (Internet Explorer 8)
If you are using Internet Explorer 8 and your internet is running slow you should undo the immunizations or remove Spybot completely.
Malwarebytes free is the recommended alternative malicious software removal tool. Be aware that the free version does not provide the blocking (immunizations) that Spybot did. Malwarebytes does not replace the use of a good antivirus. It should be thought of as a second opinion as to your security status.
Malwarebytes can be purchased to provide the additional "Real-Time" protection (blocking) but this feature may already be a part of your antivirus product. If your current antivirus product has "Spyware" or "Malicious Software Blocking" abilities they may well conflict with the paid version of Malwarebytes. The paid version of AVG antivirus already provides these features via it's "Web Shield" and "Anti Spyware" parts.
If you are running a free antivirus (never recommended) you would benefit from purchasing the full version of Malwarebytes to supplement your protection as "Free" antivirus products are often stripped down versions of a better "Paid" versions.