Ambulances took over an hour to arrive for high priority calls more than 500 times in the first six months of this year.
In some cases, delays of up to four hours were reported following calls to the National Ambulance Service (NAS).
However, the service did say there were no one-hour plus delays in the highest priority category of incidents in the first half of 2024.
A breakdown of calls that took more than 60 minutes to respond to showed that the highest number, or 77 separate emergencies, were in Cork.
Other counties with a high rate of lengthy response times were Wexford with 41, Tipperary with 35 and Kilkenny with 34.
Under the NAS system, around 48 per cent of calls are categorised as either PURPLE or RED where they are considered life-threatening or potentially life-threatening.
For the most serious ‘PURPLE’ calls, a target of responding within 19 minutes in 75 per cent of cases has been set.
During the first two quarters of this year, the NAS was just over target at 76 per cent with no emergencies taking longer than an hour to respond to.
For the second-highest priority ‘RED’ calls, a response target of reaching 55 per cent of calls within nineteen minutes is in place.
However, the NAS performance between January and June was 47 per cent with a total of 504 calls not responded to within an hour.
All three of the longest waits were in Co Cork, with a response time of three hours and 57 minutes in the worst case.
There were five cases in total where the delay exceeded three hours, according to data released under Freedom of Information laws.
A further 22 high priority ‘RED’ emergency calls had a response time of between two and three hours.
There were also 477 cases where the time a patient was left waiting exceeded 60 minutes but was less than 120 minutes.
Counties where prolonged delays were least likely included Longford with just three one hour-plus delays, as well as Laois and Sligo which both had five.
The National Ambulance Service said pressure on them continued to grow with an 8 per cent rise in calls in 2024 compared to last year.
They said a capacity deficit of 90 emergency ambulance crews had been identified in September 2021.
An information note said: “Performance targets set out in the HSE National Service Plan reflect the level of performance expected based on the level of resources available.
"The response target for RED (Delta, life-threatening illness or injury, other than cardiac or respiratory arrest) is 45 per cent in 18 minutes, 59 seconds."
