The 5.7 manual says (http://dev.mysql.com/doc/refman/5.7/en/mysqldump.html#mysqldump-performance) "for large-scale backup and restore, a physical backup is more appropriate, to copy the data files in their original format that can be restored quickly", and recommends the MySQL Enterprise mysqlbackup utility.

If that's not feasible, http://dba.stackexchange.com/questions/13446/slow-load-speed-of-data-from-mysqldump describes many tweaks for restoring from mysqldump backups.