Wooden slabs is used on a pickaxe not an axe

Put the summary of the bug you're having here

What I expected to happen was...:
I was trying to destroying a wooden slab, and this was a old bug too.

What actually happened was...:
And then when i was trying to destroy the slab with an iron axe it was slower and then i used a pickaxe which is faster

Steps to Reproduce:
1.You must have a Wooden slab placed down
2. Try to destroy the slab with an axe and its way more slower
3. Try to destroy it with an pickaxe and its faster