You may have saved the VI with the controls and indicators set with the 100K elements as default. In that case the arrays are saved in the VI and it wil take up a lot more space than the code would...
Working with large arrays there are a number of pitfalls (most of which involve continously copying and resizing the large arrays using the build, insert, delete and other array functions that have to do that or locals and globals). The quickest way to know would be to post the work here, or an example (remember to upload all sub-VIs etc). You can also find lots of info on this if you check out the optimization part of the manual and run a search on that here.
