SQLite Forum

partial file load?
From that evidence, it is reasonable to guess that SQLite reads the whole DB file upon open. But it is unreasonable to conclude so. As Richard says, SQLite reads in what it must to satisfy queries. It does read in whole "pages" at a time, so that "must" includes portions of pages which may not be strictly required. Possibly, your large DB files have bigger pages, which would include the one(s) in which the sqlite_schema (aka "sqlite_master) table resides.

You need to discover why all that disk activity is occurring. There is no SQLite option to avoid it because SQLite avoids it without being told. Your SQLite library wrapper might be responsible, or there may be things happening not yet apparent to you.  (Those are my guesses.)