Complete list of new features in MySQL 5.7 [0] (in bullet form) would show scores of performance improvements. The performance improvements from 5.5 to 5.6 were significant and 5.7 is much much better.
(I am the Product Manager for the MySQL Server, but yes - I personally own the domain.)
[0]: https://m.reddit.com/r/zabbix/comments/3txgov/poor_performan...
MySQL 5.7 changed the cost-model significantly, so while it will be better on most queries, there are cases where two-wrongs-made-a-right; and edge case queries may be slower. To mitigate this (as it was somewhat expected), MySQL 5.7 also introduced new query hints and server-side query rewrite.
(In the case of the link you provided, OP responded later saying 5.7.10 improved performance again.)