Domestic box office is still running 2.5% behind the pace of 2010, which already had its “Twilight” installment on the books by this time. But even if “Breaking Dawn — Part 1” hits the highest estimates of $150 million — one of the highest domestic bows of all time — don’t expect 2011 to come any closer to pulling even with last year.

That’s because Warner Bros.’ “Harry Potter and the Deathly Hallows: Part 1” launched this same weekend last year to a similarly B.O.-shattering $125 million, the seventh-highest domestic bow ever.

“Breaking Dawn” expands Friday to 4,061 locations after 3,251 Thursday midnight screenings. Though some tracking services say it could hit north of $150 million through Sunday, Summit has far more modest expectations, ranging between $110 million and $125 million.

Unlike this weekend last year, which had little else among new entries, this weekend’s family-targeted 3D counterprogrammer, “Happy Feet Two,” will boost the weekend with expectations in the $32 million-$35 million range. Warners launches the film today at 3,606 Stateside locations, of which approximately 2,800 are in 3D, with 293 Imax locations.

Fox Searchlight’s “The Descendants,” meanwhile, expands today to 29 Stateside locations, after bowing Wednesday at five playdates to a solid opening-day per-screen average just shy of $8,000.

“Breaking Dawn” already is off to a solid start in overseas territories, including Australia and France, for a total estimated $8.9 million. In Gaul, the film scored $3.8 million, making it the country’s third-highest opening day, behind “Deathly Hallows: Part 2” and “The Adventures of Tintin.”

The second-to-last “Twilight” pic, released internationally via local distribs, opens day-and-date in a total 54 countries outside the U.S.

Summit launched the third “Twilight” film, “Eclipse,” during summer 2010, with an opening six-day domestic tally of $158 million; the franchise’s second pic, “New Moon,” opened Nov. 2009 with $143 million.

Observers say the 16-month delay between “Eclipse” and “Breaking Dawn” likely helped build anticipation for the latter pic, as well as decreasing “Twilight” oversaturation. By comparison, the series’ second and third installments had only an eight-month release gap.

Budgeted at a reported $110 million, “Breaking Dawn” is headed for the fast track toward profitability.

The film will play best with females of all ages, which could hurt “Happy Feet 2,” as moms may be preoccupied by “Twilight.” Toon should have a strong hold among families with tykes, contending only with fourth-frame holdover “Puss in Boots.”

The opening 3D share for “Puss,” at 51%, points to so-so business for “Happy Feet” in 3D. Summer toons like “Cars 2” stalled with the format, with 40%, while similar 3D family pics around this time last year, such as “Tangled” and “Megamind” did better in 3D, with 56% and 66%, respectively.

Warners isn’t expecting “Happy Feet Two” to match its predecessor, which opened to $41.5 million in 2007.

Fizziology, which specializes in monitoring social-media sites, reported that both “Happy Feet Two” and “Breaking Dawn” have a 70% positive rating from all social-media posts. The company also said that “Happy Feet Two” has more online interest than “Puss in Boots” and “Kung Fu Panda 2” did.

Now it’s just a question as to whether that chatter can translate into tickets sold.