No. The development engine uses indeed more memory for internal diagnostics, but the difference is in the ~1 MB range.

From what you posted so far, the problem was never solved. Do not ignore such a problem during development. You should always have an idea which memory your game resources require. When it's suddenly 1 GB more than you expect, you better care about that before doing anything else.

Check the memory indicators in the status panel - they tell you when something uses an unusual amount of memory. This should help you to find the problem. F.i. when it's the nexus, the reason is an object in the level; otherwise it could be a media file or something you allocate in the script.