Efficiency is a type of Ratio. Efficiency is a synonym of Effectiveness. Learning can cause/lead to Effectiveness. Learning is related to Introduce. 
Delay is a synonym of Hold. Bucket can be used for Hold. 
Ratio <--IsA-- Efficiency <--Synonym--> Effectiveness <--Causes-- Learning <--RelatedTo--> Introduce 
Delay <--Synonym--> Hold <--UsedFor-- Bucket 