Active Records Performance vs Raw Queries

This sounds the same as Template Engines vs Plain PHP (why to use Temp.Eng. when it finally generates and run plain php)..

Same is and with Plain SQL vs QB .. At the end you always have execution of plain SQL query.
Its normal that if you write it directly it will be faster than building it with some PHP classes.

For easier managing of the application I think that its better to use QB, but when there is some specific need (usually complicated queries) plain query is always an option.

Best VPS Hosting : Digital Ocean