In a week when former DPP solicitor Lisa Munro was placed on a good behaviour bond after pleading guilty to one count of cocaine possession, a long-standing judge unleashed on the office for its alleged "incompetence" and "inefficiency" in a separate case.

Questions are now being raised about whether the apparent problems inside the office stem from a lack of resources, with the NSW Labor Opposition pointing to a number of unfilled prosecutor positions.

"The workload of Crown prosecutors is prodigious," said one criminal lawyer in Sydney. "The moment they get something out the door there's three more briefs on the desk. It's a high pressure lifestyle."

The number of Crown prosecutors in NSW has remained largely steady over the past four years, at about 79 full-time equivalent positions. In response to questions on notice following budget estimates in September, the Department of Justice said there were four vacancies for prosecutors and a "$3.9 million underspend in wages [last financial year] is primarily due to vacancies".

There was a corresponding overspend of $4.4 million in other parts of the budget to retain private barristers to act as prosecutors.

Shadow attorney-general Paul Lynch said this was "consistent with anecdotal stories of delay in the DPP Office" and "this significant underspend just adds to the unease that some have felt about the Office of the DPP".

"If the gaps are filled by using the private profession that is both more expensive and less efficient," he said.

But the ODPP told Fairfax Media it had overspent its budget last year and had appointed eight new Crown prosecutors over the last few months, evenly split between men and women. More appointments were expected in the coming months.

"Four of these new appointments came through the ranks of the ODPP," it said. "Further, three female Crown prosecutors have been appointed judges in the last year, reflecting the respect that this office is held in."

Attorney-General Gabrielle Upton said she had full confidence in the Director of Public Prosecutions, Lloyd Babb​, SC, and the office's budget had been increased by $9.3 million to $127.2 million this year.

"This sizeable funding boost will primarily go to hiring more prosecutors," Ms Upton said.

Acting Justice Robert Shallcross Hulme took aim at the DPP on Tuesday after he was forced to vacate the impending murder trial of alleged Brothers for Life gang leader Mohammed Hamzy because the Crown had not disclosed relevant information earlier.

"I have now been, or acted as, a judge of this court for over 20 years and I never cease to be surprised at the extent of the incompetence or the inefficiency within the office of the Director of Public Prosecutions," he said.

But in rare public comments, Mr Babb said "His honour's comments are not a fair representation of the performance and dedication of the numerous hard-working lawyers who have worked on behalf of this office over the last twenty years" under three different directors.

Many of the office's prosecutors "have gone on to be appointed magistrates, District Court judges, Supreme Court judges, and Senior Counsel of this state", Mr Babb said.

On Thursday, District Court judge Peter Berman criticised delays on both sides as he was forced to delay the sentencing of Puipuimaota Galuvao, who pleaded guilty to dangerous driving which caused the death of a 16-year-old schoolgirl.

"I think Justice Hulme had something to say about prosecution inefficiencies. This is not good enough," Judge Berman said.

The ODPP said "there was a joint application for the matter to be adjourned" and "of the thousands of matters dealt with in the NSW District Court each year, a tiny percentage of them involve an application by the NSW DPP for an adjournment".

Earlier this year, Mr Babb received allegations of drug use about Ms Munro, a former member of the ODPP's elite "Group Six" that deals with high-profile cases including referrals from the Independent Commission Against Corruption.

A police investigation uncovered no evidence of any drug use in the ODPP and there is no ongoing investigation involving the office. But Ms Munro was arrested in July as part of an unrelated drug operation, when she was found with 0.65 grams of cocaine.

The 33-year-old quit her "dream job" after her arrest and pleaded guilty to one count of possession but has escaped conviction and jail time.

with Rachel Olding