I rode the S79-SBS yesterday, I have to say it actually is pretty quick (though it can be busy depending on the time, PM rush hour is something you should avoid). Generally, it can take about 45 to 60 minutes from SI Mall to Bay Ridge 86th Street.
Though, without a doubt, the fastest way to get to Brooklyn is the S93 but due the the pandemic it isn't running unfortunately. It leaves with me with either the S53, which is faster than the S79-SBS as I live closer to it but it is pretty boring to ride.
Change of topic here;
When I lived in Brooklyn, I lived close by the B35 which, before Jackie Gleason was bestowed the XN60 articulated buses, I'm pretty sure it only ran C40LF's. Even earlier, it had Orion VII's which operated both the local and limited B35. I never expected such an articulated bus to jump on this route, what a change of equipment. Though, it makes sense, this route always had high ridership, I can recall a time where a bus on the B35 was so packed that, per policy, it had to skip stops until the bus acquired some reasonable space. People stuck onto the doors of the bus just so they can get on, I think someone's face was even pushed onto the door, there was absolutely no space.