Right - don't use iquery for fast exports, it is only meant to be for quick interactive use.
For opaque format, the fastest is to use
save operator as in
save( ARRAY, 'relative/path', -1, 'opaque')
That makes each instance generate an opaque file at "relative/path' inside their respective data directories. That will generate one file per instance. These files can be re-loaded all at once or one or more at a time. More info here: https://paradigm4.atlassian.net/wiki/spaces/ESD169/pages/50856208/save
For TSV or binary format, the fastest way is to use
aio_save from this plugin: