When the constraints are reenabled after importing, the entire table is checked, which may take a long time for a large table. If the time required for that check is too long, then it may be beneficial to order the import manually.
To do so, perform several imports from an export file instead of one. First, import tables that are the targets of referential checks. Then, import the tables that reference them. This option works if tables do not reference each other in a circular fashion, and if a table does not reference itself.