In creative mode, when you eat any kind of food and while eating it, you drop the item (by pressing Q) and keep holding right click, your speed is still slow as if you are still eating it.

Steps to reproduce:
1. Go into creative mode
2. Get an apple
3. Start eating it
4. Before you finish eating it, drop the item

Video attached if you do not get what I mean.
When you release the right click button, your speed is back to normal.