I have stomp record max now to create dvds

I have a pioneer dvdr 105 writer and use 4x disks, when burning starts the time left for completion will be around 15mins, but after a while it boosts up to over 30mins and even 45mins so it cant b writing at the full speed

my firmware is 1.30

ive tried using copytodvd software to burn a dvd

At the bottom corner it says
Instant Speed x2.0 avg x2.0
the instant speed is varying up and below the x2.0 mark so im definitley not burning to my dvd writers potential

ive tried some different disks

anyone got any suggestions on what i can do, as waiting around 45mins per dvd is mad