Only half of the most risky house fires in Northern Ireland are reached by firefighters within six minutes.
The proportion of engines meeting the 999 response time target has fallen over recent years, according to an annual report from the Northern Ireland Fire and Rescue Service (NIFRS).
John Dallat, an SDLP Assembly member for East Londonderry, said: "It is alarming that performance, rather than improving, is worse."
The dated targets are being revised to include other risks like flooding, which have become a more significant part of the job.
Although last year's report did laud good work done by the service in a series of areas, comptroller and auditor general Kieran Donnelly voiced concern about a range of governance issues surrounding how the NIFRS operates.
He said: "NIFRS should not continue to be left vulnerable to risks from failures in internal controls.
"I shall continue to monitor this situation and would expect to see another considerable improvement in addressing the number of outstanding internal audit recommendations in the coming year."
In high risk cases the target for response, which is being revised, is that three-quarters of blazes are reached by the first fire tender within six minutes.
In 2014/15 actual performance was 59%, the following year it was 57% and last year it had slipped to 52%. The second appliance's record against a nine-minute target was around 60% over the same period.
The report said those were optimum response times for particular areas based on the level of foreseeable risk and were used when deciding where to situate fire stations and equipment.
It added: "The current emergency response standards were introduced in 2006 and were based upon data from 1999 to 2003.
"These standards are no longer current as they are based on a risk profile of dwelling fires only and do not reflect the additional community risks associated with fires in other types of buildings, road traffic collisions and other types of calls such as flooding, rescue/release of people and incidents involving hazardous materials."
In 2016-17 the service developed proposals for graduated standards based on current risk levels. It added: "These proposals will assist in ensuring NIFRS has the right firefighters, appliances and equipment, in the right place, to provide the right emergency response at the right time."
It will be carrying out a full public consultation this year.
Mr Dallat said vacancies on the fire service's governing board meant there were no SDLP or Sinn Fein representatives to scrutinise performance.
"It is alarming that performance, rather than improving, is worse. The absence of people on the board to ask relevant questions is alarming," he said.
Mr Donnelly, while acknowledging progress has been made in addressing outstanding issues, is also still concerned.
"The rate of progress in 2016-17 has been slower than I had expected and therefore I still consider it necessary to report my concerns."