This is just a recent problem that has developed in the last few weeks. When I import AI files as a Composition, PSD files as a Composition, or previously created Compositions, it takes several minutes to import them.
There is nothing unusual about these files being any larger than anything I've imported in the past. Files of this size used to take seconds to import on the exact same Mac laptop with the exact same amount of memory. Why does it suddenly take two, three, four, five minutes to import?
Nobody can tell you anything without proper system and version info or other technical details like what the files actually contain.