2007 E60 - SMG delayed shifting between every gear, and under hard acceleration

Hello, honestly there's nothing to guess at here. A diagnostic tool is needed to monitor inputs and outputs. You can learn much from what the data tells you. When all commands seem accurate, and slipping occurs, it's an internal mechanical issue. https://repairpal.com/repair-shops/bmw-repair-and-service-in-raeford-north-carolina

E60 SMG transmission have a propensity to chew through hydraulic pumps and pressure accumulators. The hydraulic system is what's responsible for shifting the transmission, so if it won't shift properly, that's the first place to start looking. Unfortunately this is not a diagnosis a non-professional can do on his/her own. I suggest you find a reputable independent shop in your area that specializes in BMWs to fix this problem. Good luck!