I think it's better now, it handles as least 1.4GB in the heap. That said if you have a database with more than, say, 300MB of data, I think you need a more large-scale database.
As an aside, I'm considering enabling large datasets for NeDB as some users asked, but that would be a lot of work so I'll wait for more requests.
If it is, you should probably put a larger warning about dataset size than the line you currently have :)