A fifth of civil cases in the High Court take longer than two years to complete, a study has found, though on average cases take six months to wrap up.
The Otago University research found general proceedings cases took an average 13 months.
Lead author Dr Bridgette Toy-Cronin said there was "a common perception that there is widespread delay in our courts''.
If proceedings were delayed, it was a key obstacle to accessing justice and created both financial and psychological costs for the litigant. One litigant described this stress as a nightmare.
But the overall length of time a case took to be resolved didn't tell the full picture, said Dr Toy-Cronin, director of the Legal Issues Centre at Otago University's Law Faculty.
"What often happened in those very long cases was that they'd actually been parked because, for example, a settlement agreement was taking place.
"So the clock looked like it was still ticking in the High Court, but actually it was by agreement of the parties.
"They wanted their case to stay, in case something went wrong with the settlement, but they weren't actually litigating actively."
In other cases people deliberately slowed down proceedings "because they want to put pressure on the other side, or they need time to get their financial resources together to keep fighting another day, or they need that time to get evidence together to be able to litigate that case.
"If you've got two parties who really want to drive the case forward and they're both willing to litigate and go in there and get a judgement, the system works very well and you'll get to judgement quite quickly.
"But if you don't have that dynamic - if one party's trying to go fast and the other's trying to go slow or if you've got a lot of complexity and need a lot of input into your case from experts - that's when you start to get things slowing down."
A major problem was that the IT system that courts used was not sophisticated, and the system was still paper-based.
"They're printing out emails and putting them on the paper file to schedule cases and everything's on paper.
"It's very inefficient from both a court administrative perspective and also for being able to extract data and figure out how well the system's working, who's using the system, those sorts of thing."
Dr Toy-Cronin said the longer cases dragged on the more detrimental it was psychologically and financially on parties.
The study was conducted by Otago University's Legal Issues Centre and co-funded by the New Zealand Law Foundation. It included a quantitative analysis of Ministry of Justice data, analysis of physical court files, and interviews with lawyers, judges, court staff and litigants.