Streaming content is one of those big things I can think of which are missing in Gamestudio. This counts for all kinds of stuff: Bitmaps, Models, Levels, Sounds, etc.

One further suggestion: If one would stream a content and creates it with the common functions like ent_create, the streaming will be continued until it is ready and then it will automatically created by the called function.

This way, one could start streaming e.g. the next level, if the player is in the reach of the level exit. So, lets say it is big and loaded by ~70% when the level_load call is done. Then, the level_load call would wait, until the remaining ~30% of the level is loaded and then it will be "activated".

Sounds reasonable, isn't it?