SAN FRANCISCO — For some opera fans, the most startling thing about Calixto Bieito’s production of Bizet’s “Carmen” here last month was not the soldier clad only in his tighty-whities and combat boots, or the nude matador. It was the way a series of cuts had whittled roughly half an hour off the opera, which wound up taking less than two hours and 50 minutes, including just one intermission, to propel its heroine to her bloody end.

The streamlined “Carmen” here is part of a broader debate within opera. After several decades in which the trend has been toward longer, uncut operas — drawing on the work of scholars to restore rarely performed passages, and putting a renewed emphasis on completeness that would be alien in, say, Shakespearean performance, where cuts are routine — some impresarios and directors think it is time for the pendulum to swing back a bit.

They fear that three- and four-hour nights, with occasional slow passages, turn off time-pressed modern audiences. Some believe that judicious editing, which was not unheard-of when opera was younger, can speed things along for a new age when pastimes as varied as Major League baseball and Elizabethan drama are trying to pick up the pace.

But it is a tricky balancing act. Can opera companies, many of them struggling at the box office, broaden their appeal by cutting without alienating their core audience of connoisseurs, who tend to view such cuts as disfigurements close to vandalism?