I suggest you use a excel sheet with the same data structure. but with a limited set of data, and thus reducing the file size.
If you really need all the data in your app;
- My guess is that the generated domain model isn't the best you can have for this large amount of data. (just a guess, based on some experience)
- If you want to import this amount of data, extend you model using the excel import module from the marketplace, AFTER you created the model and have setup a decent domain model