Slow DVD+RW burn time

i recorded a DVD+RW 2.4X in 45-60 min. in my Nec 2500A.
i think that it’s too much time.
what can be the problem?
by the way, i have the firmware v 1.07 ( DVD+R DL write)

Depends on a few things. Let me explain …

In DVD 1x ~= 1.32 MB/s, so 2.4x ~= 3.17 MB/s

Assuming you are writing the DVD to near its capacity ( about 4480 MB ), it should take you about 24 mins.
This is theoritical and does not account for overhead … I would say anything more than 30 mins is suspect.

60 mins is about the time it takes to burn at 1x.

What is the media that you are using ? Maybe its not certified at 2.4x … Post the media code here (ADIP info).
Also how much data are you trying to write ? And finally how are you measuring the time taken - is it from the burn program or are you measuring it independently ?