We are working on a project that takes very to start, how can we decrease the time of the startup?

Some details of the project;

One very huge map with several sub-maps.

Quite a lot of script(files) for the big map and included mini games.

Dll plug in for saving to registry, the entire project is written in c-script.

I hope someone knows why it takes so long to startup the game and how to decrease this.

Thanks for reading