@billybob The speed will be reduced when you “Enforce Access Control”, but it should still be more than 50 Mbps overall. However, not all your devices need to have Access Control enforced.
You may create multiple profiles, with “Enforce Access Control” checked for some and unchecked for others. DNS filtering, safe search, black/white listing and ad blocking will remain active even for profiles with “Enforce Access Control” unchecked.
The purpose for the “Enforce Access Control” flag is to block the various ways to bypass Access Control (e.g., via proxies, VPN, DNS over HTTPS etc.), and to enforce an Internet access calendar (i.e., to force shutdown of the Internet) for certain devices. You don’t need to check this flag unless there are attempts to bypass Access Control from some devices.