Commercial airliners do have to take into account commercial viability. Therefore speeds are not exactly the fastest available ones. The currently fastest civil jets are business jets, i believe the Cessna Citation X+ with M 0.935 MMO and the Gulfstream G650 with M 0.925 as MMO are pretty much the fastest ones available, both apparently able to cruise quite comfortably at 0.92 if one sacrifices a bit of range for speed. And quite honestly, the owners are not really looking for every penny in fuel saving...