At the U.S. OOTP premiere at Grauman's Chinese Theatre in Los Angeles, director David Yates told us that they are currently working on paring down the many memories in Half-Blood Prince to a workable film format.
"We're making a decision right now to compress those a wee bit, but we've still got some really cool ones. We've got, you know, the wonderful thing is seeing Riddle as a child, which is really scary, and I've found a really interesting kid to play Riddle. I can't tell you who it is yet -- it's early days."
Producer David Heyman later expanded on Yates's comments.
"There will be memories, but not as many as there are in the book." When I asked which ones they're cutting, he said, "I can't say that yet because it's still a work in progress. We haven't locked up the script yet."
The Gaunt scene seems to be cut as Yates recently said that they have only “2 or 3 memories”
In the books, the memories were a very big part of JK Rowling's story. We've actually pared them down in our story, and she was very supportive of that decision. They're such an enjoyable part of reading the Half-Blood Prince. But we've kind of distilled them down to two or three memories to try to keep everything more in the moment. Flashbacks in movies are tricky things; they tend to hold up the momentum of the story you're telling.
Test screening viewers confirm that the Gaunts are cut and that the “2 or 3” memories are the orphanage and the fake and real horcrux memories.