This is actually one of the few verisimilitude sticking points for me
This is actually one of the few verisimilitude sticking points for me (particularly with blinding barrage).... level one rogues shooting 9 times with a crossbow in 6 seconds is a bit of an issue.
The crossbow is “load minor,” which means it requires a minor action to load a bolt into the weapon. If a power allows you to hit multiple targets, the additional load time is accounted for in the power.
By RAW, it isn't an issue - see PHB1, p217: