All things equal, Step Intent swings should generate higher speeds than regular Max Intent swings.
However, Step Intent swings are more challenging to execute with proper mechanics. As such, it is common for Step Intent swings to initially be slower until proper mechanics are achieved. Even though your speed may be slower, it is worth challenging yourself to execute the proper coordination. There are two benefits:
1. Learning mechanics that are more advantageous for clubhead speed.
2. Once learned, the added speed will enhance the training stimulus.
If timed correctly, Step Intent swings will increase the contribution from the ground reaction force under the lead foot. This will add more angular momentum into the system.  More angular momentum in the system gives more potential to increase clubhead speed if this momentum can make it from the body out to the club. You should be stepping forward as the your backswing is still being completed, which will help add a stretch in the torso and lead shoulder muscles. It will also help to focus on maximizing wrist lag in these swings.
If you are struggling to swing faster with a step, then try to scale back the amount of "step" until progress is made.  Initially, just try to feel an exaggerated weight shift, then progress to a slightly narrower stance with small step.