when the ASC light comes on, this means that there is a fault is the traction control system of the car. This system is able to cut throttle input, so, a malfunction here can impact the throttle response of the car.
additionally, a failure of this system can also sometimes cause a transmission fault, which can lock the transmission in high gear and force the car to move slowly. This does not seem to be your issue if the transmission is working, but it was worth mentioning.
The other possibility would be an unrelated transmission or engine malfunction, but you do not have any warning lights which point to any issue other than a traction control issue at present.
The next / only step at this time will be to have the computer fault logs read out of the traction control system using a compatible diagnostic scanner at a BMW garage. This is the ONLY way to diagnose an ASC warning light.
Sorry if you were hoping for a different answer, please don't shoot the messenger - I can only give the honest answer, which I have. Please remember that a low rating PUNISHES me for my honest and prompt response, and I receive nothing for my time and answer until a positive rating is clicked.
Please let me know if you have further questions. Please do not forget to click a positive rating as this is the only way I receive credit for my answer, thank you. Best wishes with your vehicle.