Our proprietary method of filtering Internet content allows us to remove the bad stuff without impacting your existing Internet speed, and in many cases will improve it.
Out of the box the bad stuff is blocked, and you should notice no difference in your Internet speed. However you could introduce a slow browsing experience if you create many firewall > restriction rules (i.e. device specific or global Internet access restrictions), and that depends on what kind of rules you apply. For example, blocking domains / websites is fast, but applying regular expression rules to all devices can introduce latency. These are rare situations, but possible, and easily resolved.