How to reproduce:
1. Open the attached project
2. Play Test scene in editor
3. Press the button "Download from the Cache"
Result is around these values:
Loading Time was - 00 : 00 : 163
The Instantiate Time was - 00 : 00 : 15

4. Press the button "Download from Streaming Assets"
Result is around these values:
Loading Time was - 00 : 00 : 16
The Instantiate Time was - 00 : 00 : 12

One can notice that loading asset bundles from Streaming Assets is faster than from cache. The bundles are uncompressed for both cases.
Note: if you want to test on Android or iOS device, you should rebuild asset bundles. And move it from ProjectName/Build/android or ios/uncompressed/art to Streaming Assets/uncompressed

Results on Android device are same to the ones you see from editor.
Results on ios device are a bit different:
From cache:
Loading Time was - 00 : 00 : 334
The Instantiate Time was - 00 : 00 : 75
From Streaming Assets:
Loading Time was - 00 : 00 : 48
The Instantiate Time was - 00 : 00 : 37

Reproducible: 5.5.3f1, 5.6.0p1, 2017.1.0b1