It has come to our attention that changes in the behavior of the Android Build Tools (starting with version 25? we are unclear on the exact number) can affect the performance of device database loading times of the Vuforia SDK.
For smaller databases (less than 10 images), the effect may not be noticeable. However, for larger databases, the time to load can take several seconds or longer.
Our analysis has determined that the updated Android Build Tools are now compressing the device database files within the APK, rather than just storing them in their native size as downloaded from the Vuforia Target Manager. As the .dat component of the Vuforia device database is already a zip file in itself, the compression produces little gains with respect to the overall size of the APK, but can be costly when reading the data upon app start.
We found that the compression of the .dat file can be prevented by adding the following to the build.gradle file:
Note that loading device databases from external sources (such as /sdcard, or the app's private file space) are not affected by this change. It is particular to device databases that are packaged with the APK.