Completing Memory Sequence 9 in under 7 minutes is quite easy. It can be done in under 6 minutes for the "Increased Smoke Ammo" upgrade. You can save a lot of time by jumping instead of running. The hardest part is the Boss fight at the end. Sometimes the Boss runs away and hides in the crowd, which can cost you a lot of time. The best way to deal with this is by restarting the checkpoint when it takes too long. Additionally, cutscenes do not add to your time. There is also no penalty for restarting checkpoints.