While playing on a creative world I have equipped an Elytra and started using the creative mode flight. Once at a high enough height I decided to switch to flying with the elytra and rockets to move faster. Once I dropped from Creative flight mode by double tapping space bar, I activated the Elytra wings, even had the mini player in the left hand corner was showing myself in elytra mode, but no matter how many rockets I spammed I could not pickup any speed. Then While gliding on the elytra I pressed space bar and the character gained altitude. Pressing shift while flying with the elytra has no affect though. I have to exit the world or get on  solid land to break the slow fall affect. Could not duplicate on an android device.