Since you live in San Jose, you can borrow a Sega USB I/O and see if it gives you any issues. They are the same exact size and the pinouts are the same too. Plus, they have USB, so you can use it on a PC (D input only). Drop me a DM if you re interested.
That is the official Sega I/O that comes in Naomi Universal, Net City and New Net City.
When I used to have a New Net City, I actually replaced this I/O for the Sega USB I/O (type 4) and it worked great for most games. It did not like the Y2 system though (KOF 2002 Ultimate Match).
That's an X3 if you're running the Artax 4.1, this thread is for the X2. And FYI, your issue on your X3 is that the security is enabled and you need to disable it again.
You can use fast I/O. Maybe put your image on a SSD. Or maybe it's your monitor that's laggy?
You need to give more information about your setup for people to give you advice.
I wanted to share that the patch works great for the carts that @rewrite did. This sure beats power cycling to select a new game. I highly recommend it for anyone who owns the Vortex multi.
I have a few original, legit PCB I am selling for a friend who just had a baby and needs the money more than he needs the games. I will post pictures of the board once I get the chance.
Prices DO NO include shipping. Local pickup is also available. PayPal F&F only. Not looking to ship...