Imagine a professional CS-GO game with a huge prize pool, but one team plays over a slow Wi-Fi connection, and the other team over an ultra-fast gigabit fiber connection.
That's a bit of an exaggeration, but it beautifully explains what DoubleZero does for validators and high-frequency traders:
DoubleZero is building a parallel internet for high-speed applications, often 100x faster than the typical validator connection.