Google page for netguard+ntl click here.
A no. of people have complained that the sw can seriously affact the speed of your pc. Sometimes this happens straight away, and others over a period of days.
Don't use it myself, but have some clients that did until they had the above probs. I uninstalled for the and put avast free on instead. On two (out of 5) who used it and wanted it uninstalled, the uninstallation was not straight forward, had to resort to restore.
Should point out that I know 2 people who are perfectly happy and have not suffered any probs with it at all.
Hope this helps.