The size of your qvw document on disk is more or less irrelevant, it's the data model, the sheet objects and the uniqueness of data that matters. But I would say that 300 MB on disk to 30 GB in memory is pretty good work.
How much does the document take in memory if it is preloaded alone? How many users are accessing the document?
ziangi99: If you are having 350 users in you document, 30 GB is not very surprising. User behavior results in cache, and on a unoptimal data model, that can cause large memory usage. Are you using dynamic reduction?