AssetBundles vs Resources Speed to load

I have various scenes saved as prefabs. The prefabs contains everything for the scene in a single empty except standard objects like player, sky, etc that will be used in all scenes.

I was storing these scene prefabs in the Resources folder and instantiating them from there until I started to get memory allocation errors on attempting to build if had a lot of scene prefabs.
So I changed them from resources to locally stored assetbundles.

The trouble I am now having is that scenes which took 5 seconds to load from a resource now take 25 seconds to load from asset bundles.

Is there any way to get round this speed problem? Resources seem the better option but then I get the crash on build.

This is what I noticed as well. I found the info that it could be because I didn’t build it properly, and it did not pass the Uncompressed flag, but there was no details to explain what this exactly means.