I have been developing a mobile application on Flutter-Dart.
I use MySQL database and python for the backend.

But for some data to be exchanged quickly and fast as much as possible, MySQL (or MSSQL or any other similar databases) doesn’t provide satisfying performance. Especially when I consider big amount of users e.g. 30K+ users, the performance will reduce remarkably. I already store some of the data such as the user’s personal information on the sharedpreferences storage of the mobile application and sync. only when required.

I store a user’s basic data information such as a smallint or boolean single-cell-information for e.g. online-offline status, dynamic preferences.
I don’t know which technology would be better to be used for storing and updating these kind of quick data, instead of storing them on MySQL or large-size database.

I have searched some technologies such as but wished to ask you experts for not spending a lot of time for searching. Because there are also new technologies but may not reliable for the future use to be used,since the support of some of open-source tools (especially small ones) may end the patching.

PS: I don’t want to use 3rd party database services such as Firebase or Amazon or similar.

Thank you for your helps.