Steps to reproduce:

1) Download attached project 'Client.zip' and open in Unity.
2) Open scene 'GridStreamerFly2D_2x2_Potisioned_LightingMatchTreeScenes' in Client\Assets\_ForUnity\GridStreamerFly2D_2x2_Potisioned_LightingMatchTreeScenes.unity
3) Press Play.
4) Press Left Shift to enable fly camera
5) Fly forwards ('W') and upwards (mouse up slightly, 'W') to get into the first world cell.
6) Fly right ('D') until the next tile loads.
Notice the frame rate glitches when it loads.

For more details to see actual results, check video attached 'streaming-framerate-glitches.mp4'.

Reproduced with: 5.3.6f1, 5.4.0f1, 5.5.0a3.

Note: In 5.4.0f1, 5.5.0a3 loads scenes smoother, but you still receiving visible frame rate drop.

Expected result: no frame rate spikes, scene loads in the background.

----------------------------------------
Fixed in: 2017.2.0b2