ATLANTA — Travelers who were dreading long airport security lines before the Memorial Day weekend instead reported moving quickly through checkpoints Friday after authorities opened extra screening lanes and used bomb-sniffing dogs to give some passengers a break from removing their shoes.

“Wow. I mean, wow,” said Mike Saresky, who flew into Chicago from Philadelphia, where he breezed through airport security in 12 minutes and got to leave his shoes on. “I thought it was going to be a lot worse.”

The extra dogs were concentrated at the nation’s largest airports, but they were not used for all screenings, meaning that many travelers still had to observe the usual procedures.

But as the busy summer travel season kicked off, the federal Transportation Security Administration tried to offer travelers some relief after weeks of slow-moving lines blamed on an increase in the number of air travelers and a shortage of TSA security officers.

A TSA spokesman said the extra dogs would remain well beyond the holiday.

At Hartsfield-Jackson Airport in Atlanta, known as the world’s busiest, all 16 security lanes at the main checkpoint were open Friday morning as a bomb-sniffing dog and its handler walked among waiting passengers. Wait times were slashed to less than 15 minutes, compared with backups of nearly an hour in recent weeks.

“All the natives were telling me, ‘Brace yourself,’ ” said Carl Pluim, who arrived in Atlanta to fly home to Denver. “I left myself two hours before my flight, so I think I’ll be OK.”

When she flew barely two weeks ago, LaGretta Watkin recalled security lines that were “so chaotic” that travelers “could barely move.”

“But today it’s smooth sailing and refreshing,” Watkin said as she started a trip from Atlanta to Jacksonville, Florida. “And I’m loving it.”

The TSA began deploying extra canine teams to the busiest airports months ago. While the goal was to shorten waits at larger airports, the reshuffling could also result in longer lines at airports that lost dog teams.