What algorithms can provide accurate displacement data with MAG data for short-term applications?

I understand that IMU sensors are not perfect and result in errors (noise and drift) magnified by double integration. Specific algorithms that attempt to "clean" this data (Kalman Filter, Low Pass Filter, etc.) may not be a complete solution for my project because I require position tracking accuracy on the scale of millimeters. However, I only need to track position for 200-300ms at a time, with a gap of ~300ms. I suppose, an extremely fast calibration algorithm would do the trick? If you could point towards any past projects or resources that have done something similar, I would greatly appreciate it!