The star, who plays character Bellatrix Lestrange in Harry Potter and the Order of The Phoenix, admits the excessive waiting time was frustrating as she had such a small part.
She says, "I had five lines in that. I think they cut three of them - and I was there for six weeks.
"I don't know quite how, still, to this day, I was there for that long. It really is 90 per cent waiting. I mean, nice waiting - waiting's OK if you have a nice trailer.
And Bonham-Carter insists that while it was an enjoyable experience working alongside veteran UK stars Alan Rickman, Richard Griffiths and Gary Oldman on the movie, it wasn't a career-defining moment.
She explains, "It's like a rest home for British Equity, and we're all lying around and chatting. You can't look to huge job satisfaction, but it's nice to be part of it."
Source: WENN