Brute Force is better than Rtree ?

[ZZJ929464347]

why?
(30000, 'points')
('Query box: ', (1240000, 1010000, 1400000, 1390000))

Brute Force:
(50, 'hits')
4772.89 usec/pass

Memory-based Rtree Intersection:
(50, 'hits')
10586.27 usec/pass

Disk-based Rtree Intersection:
(50, 'hits')
11081.10 usec/pass

Disk-based Rtree Intersection without Item() wrapper (objects='raw'):
(50, 'raw hits')
96.34 usec/pass