Scores of Meta employees have been laid off this week, as the company embraces a new corporate culture of “efficiency” around resources and headcount.

Around 100 people were impacted by the latest round of reorganizations and a related reallocation of some resources inside Meta, three people with knowledge of the company told Fortune. Such changes and related incremental cuts to teams have been frequent at Meta this year, as CEO Mark Zuckerberg sticks to his vow that 2023’s “year of efficiency” would become a “permanent” part of how his company operates going forward. A handful of workers at Instagram and Messenger were cut earlier this year amid other team reorganizations and the elimination of certain job titles.

This week’s cuts mark at least the third time this year that incremental layoffs occurred at Meta. This time, it mostly impacted people working in Instagram, Facebook, and Reality Labs, according to the people familiar. Many of those affected were software engineers whose specific roles were eliminated, but some jobs in monetization were also cut. The Verge first reported that layoffs occurred at Meta, although none of the specifics have been reported.

Most of the people impacted received several weeks of advance notice that their roles were being either eliminated or moved to a new team or location, and were allowed to apply internally for other jobs made available to them. Some were successful. Some were not. Others accepted four months of severance in advance instead of going through that process, according to the people familiar.

The layoffs are separate from a disciplinary action Meta carried out last week that saw about 20 people in its Los Angeles office let go for improper use of GrubHub credits. The credits were given specifically for workers to buy meals while working at the office, but some were found to have used the credits for personal items or home delivery over the course of several months, as first reported by the FT.

Meta, which had 70,799 full-time employees at the end of its most recently reported quarter, cut tens of thousands of employees over the course of 2022 and 2023 in the wake of the pandemic. While the company has not had such mass layoffs in 2024, team-specific reorganizations this year have felt “constant,” one person told Fortune, noting that Reality Labs seems to go through a re-org “every few months.”

Another person said that while such changes have long been a part of Meta’s operation, a new push toward work on AI projects means more and more resources are being directed to AI and infrastructure teams. The company is also going through a process of “remapping” roles, deciding where the bulk of specific teams will be physically located given a three-day in-office work mandate that has caused some jobs to be moved or eliminated, the person said.

“A few teams at Meta are making changes to ensure resources are aligned with their long-term strategic goals and location strategy,” a Meta spokesperson told Fortune. “This includes moving some teams to different locations, and moving some employees to different roles. In situations like this when a role is eliminated, we work hard to find other opportunities for impacted employees.”

However, not all of the people laid off were given such notice, two sources told Fortune. Several people were “surprised” by emails that hit their inboxes this week explaining that their last day of work would be this Friday because their role had been eliminated. “Everyone was not treated the same in this,” one of the people said.

Several laid-off employees were in their jobs for one year or less, according to two of the sources. Jane Manchu Wong, who gained online notoriety for reverse-engineering incoming features for social media platforms before they were announced, joined Meta last year to work on its newest platform, Threads. However, she moved this year to a team within Instagram that was impacted by this round of layoffs. Wong posted that she was impacted by the cuts on Threads. However, no one working on the Threads team was laid off.

Despite the incremental nature of this recent round of layoffs, workers within Meta are expecting more such cuts, either later this year or early next year. Although the company is hiring more, headcount is being kept “very tight,” the person said, and performance reviews are tougher than ever.