The bug
Typing in the search bar of the recipe book displays the next variant for recipes with multiple variants.
How to reproduce
Make sure you have at least two bed recipes
/recipe give @s minecraft:white_bed /recipe give @s minecraft:orange_bedSet the maximum FPS to 10 (see MC-116625)
Open the recipe book
Select a tab where the bed recipes are visible
Click on the search bar
Type some characters
→ The displayed bed variant changes faster than without typing
Not completely fixed for 1.12-pre3. While using the arrow keys does not display the next variant anymore, normaly typing still does