Consider using the swoole extension. Some applications can run 30 times faster. Be sure you understand how it works.
Use cache wherever possible in order to reduce the amount of DB queries. Optimize the DB queries too, these are often the performance bottleneck of any web application regardless of the stacks / frameworks that are used.
varnish for full page caching & redis for session caching but it’s the best choice IMO.
Read Tons of More Tips on PHP Performance Optimization.