The bug
When breaking stone slabs with efficiency 5, I noticed that the slab variant was breaking much slower than the block. The full blocks were instant-mine, however the slabs took much longer to mine.
Affected blocks
This list may be incomplete.
Stone
Quartz
Stone Bricks
Linked issues
duplicates 1
Comments 3
Duplicate of MC-53641?
Added stone and stone brick slabs to this ticket. This might be intended, I'm not sure.