this question is a little missy it should be parted down to 3 parts :
Which is faster Mysql or Redis ?
can you compare mysql with redies ?
who is responsible for the speed of the job itself?
Do my application really need to know the difference when my application have not to many jobs ?
So first
Redis is slower than mysql if you are using the client php api
Redis is faster if you are using C-extiontion (https://pecl.php.net/package/redis)
when you scale up and you have too much writes to your queue Redis rock because all it is about is handling read and write within a cluster.
the job it self depends on you code and your server , the queue is all about providing an infrastructure for reading and writing to queues .
the time needed for the job depends on your side .
Final thought for bigger apps , use predis c extension , for smaller app , just go with my sql .