It's one of the things that the new NMCI uses to help protect our networks, and though I haven't done a lot of research on it, the latency between keystrokes and when they actually get shown on screen has led me to look at how exactly non-DoD websites are "isolated".
Welp, come to find out...
Menlo Security isolates browsing activity away from end user's devices and onto remote, cloud servers that they operate. This server is completely separate from the user's endpoint and business networks, meaning they are fully protected from any threats the user may come across in a browsing session.
What I take that to mean, then, is that each rendering window within the browser that displays content from a non-DoD site is being shown in some kind of plugin that tunnels from this system through to Menlo's systems, which is why everything is so terrible and laggy and just otherwise garbage.
I'll say this: if this is what we can expect in the DoD if/when we decide to move to thin client-driven computing...
I'm glad I'm retiring soon.