Cache one large object and read from cache fast for flask
Flask-Cache uses the Werkzeug cache, which uses the pickling library to serialize any cache values to a binary blob, so the value can be saved in any backend. Pickling and unpickling a 800MB object could take quite some time, especially if it's not just one big string or something "simple" like that.
At this point, i think it's better to write your own cache, tailored to the backend you use and the type of data you store.