First, "lag" isn't an appropriate term to use for Fight Sticks. There is no "lag" in the system, electrons are going to flow at the same rate always. What people call "lag" is actually system response time or latency.
System response is the time measured from a button signal being sensed by the PCB, in our case the Brook Universal Fighting Board, to it sending the command over the USB cable plugged into the console. Ideally, this should be as fast as possible. Naturally, this is dependent on the UFB's hardware make up and code efficiency. Since the hardware is constant, there is a theoretical maximum speed the board can operate which is about 20Mhz, or about 20,000,000 cycles per second. Because the code has over head, its probably safe to assume a 20% efficiency factor meaning that the board really is polling for key presses about 4,000,000 times a second. That's really fast! These numbers aren't confirmed and are subject to firmware changes over time. I present them here for the sake of understanding only.
Now, back to the EZ BUILD system. The EZ BUILD system is glorified wiring harness. It makes wiring the buttons, lever, and such to the Universal Fighting Board or PS360+ easy. There is NO processing done on the board, so there is no latency added to the system.