Yes, you can decrease the size of the vislist when using compiled objects only. In addition, you can try to call strip() on compiled objects. It has some drawbacks regarding the PolygonManager, but just give it a try. It won't help performance but it will free some memory.
If possible, share meshes. This helps for both, compiled and uncompiled objects. I.e. If you models are using the same geometry data, make sure they use the same mesh. If this is the case, objects that share the same mesh can share the same compiled data. This reduces memory usage in native and gpu memory. Have a look at Object.shareCompiledData(<Object3D>) for more information. This may also help performance wise.
And last but not least, you try if Object3D.getMesh().compress(); gives you some memory back.