Recently our [BelongsTo] relationships in ActiveRecord with the Lazy = FetchWhen.OnInvoke have stopped lazy loading. This caused some massive performance problems. Suddenly entities that were not supposed to be loading unless invoked were loading all of the time. I've been struggling with this for a couple days and just now found the answer.
Here is the property definition in question:
Normally, when retrieving an instance of "SomeEntity" the HomePage property would not load until it was accessed by some code. Two days ago, using the Nhibernate Profiler, I noticed that HomePage was being loaded...all of the time.
I tried so many possible solutions and searched for a possible answer until I came across this article.
It turns out that when you set NotFoundBehaviour=NotFoundBehaviour.Ignore on a BelongsTo relationship it circumvents the lazy loading and loads the entity anyway. I also found a bug that has been posted for this as well. Although the link rarely works well.