Hello
First of all, thank you for sharing OrbSlam library.
Second, after checking it with TUM database it appears that the algorithm is not stable:

1. Several initializations with the same database produce different results.
2. Sometimes SLAM stuck in reset mode (Resetting database) for almost all datasets from freiburg1.
3. Sometimes track is lost and SLAM exits with error.

I've noticed one smooth run on "rgbd_dataset_freiburg2_360_hemisphere" while also some initializations appear to stuck or loose track.
Also it seems to work rather slowly (5-10 fps) sometimes slower.