You got nearly 200 views.
Maybe no one knows enough to advise you.
Google maps is your friend. If you leave at 3:30 pm tomorrow, it reckons Mallow is the way to go:
3 hours 40 mins to 4 hours 50 mins
https://www.google.com/maps/dir/Dublin,+Ireland/Killarney,+Co.+Kerry,+Ireland/@52.6905642,-9.0029212,8z/data=!3m1!4b1!4m17!4m16!1m5!1m1!1s0x48670e80ea27ac2f:0xa00c7a9973171a0!2m2!1d-6.2603097!2d53.3498053!1m5!1m1!1s0x48453c0cb4976ed9:0xa00c7a9973174c0!2m2!1d-9.5044265!2d52.0599353!2m3!6e0!7e2!8j1454081400
Maybe no one knows enough to advise you.
Google maps is your friend. If you leave at 3:30 pm tomorrow, it reckons Mallow is the way to go:
3 hours 40 mins to 4 hours 50 mins
https://www.google.com/maps/dir/Dublin,+Ireland/Killarney,+Co.+Kerry,+Ireland/@52.6905642,-9.0029212,8z/data=!3m1!4b1!4m17!4m16!1m5!1m1!1s0x48670e80ea27ac2f:0xa00c7a9973171a0!2m2!1d-6.2603097!2d53.3498053!1m5!1m1!1s0x48453c0cb4976ed9:0xa00c7a9973174c0!2m2!1d-9.5044265!2d52.0599353!2m3!6e0!7e2!8j1454081400