Just dropping by in case anyone else browses this forum looking for answers... I've been using a VEC Infinity for at least four years now, and was beginning to experience similar lagging/unresponsiveness - even on a new Win10 machine with the latest version of Express Scribe Pro.
Reading Ingrid's experience here, I was inspired to consider the hardware side. Picking up the pedal, I found there were four standard screws holding the bottom plate on. Removing these, I discovered a tremendous amount of DUST built up inside the pedal! After a thorough blasting with compressed air and carefully wiping down the non-electronic side with a microfiber cloth, my pedal is much more responsive!
So if your pedal is starting to act a little old, reinvigorate it with a simple cleaning for much less than it would cost to buy a new one.
I'll try to update this post, though, if this turns out to only work in the short-term.
Cheers!
Tim