Assetbundle loading time

I noticed a very strange thing when I was checking assetbundle loading time.

I made a assetbundle which includes 117 prefabs. It takes about 40 secs on a android device to load & instantiate these prefabs from the assetbundle file by AssetBundle.LoadAsset one by one.

But when I make a new assetbundle for a scene that has references of the prefabs, it takes under 5 secs to instantiate.

I can't understand the time difference because I think two cases do nearly same jobs internally.

Do you guys have any ideas?

Below is the profiler images for the cases.

assetbundle for prefabs

assetbundle for a scene