electrons travel at the speed of light. In most cases, you can extend wires without noticing a thing.
Did you try using it with the converter but not the extension cable? (When you say converter, I think you mean you're doing a playstation hack and using a PSX->PC converter, or something similar) Some converters are naturally laggy, and extending wires shouldn't make much of a difference.
*edit* as in, get a different PSX converter if that is the case