Reproduction steps:
1. Open the attached project(prj).
2. Build and run the test scene for iOS.
3. Open the attached "stones_scaled" picture on a desktop.
4. Track and move device around "stones_scaled" picture with camera.

Actual behavior(pictures attached(scroll to the bottom of the case)):
- 5.3: small memory leak
- 5.4: spike at the beginning and a bigger memory leak
- 5.5: application crashes in a few seconds because of huge memory spike at the beginning

Notes:
- Partial regression from 5.4

Reproduced with:
- 5.3.6p7
- 5.4.1p4
- 5.5.0b6
- iPad 2 8.1.3