Max write speeds with Plextor

[Steviet]

I've been backing up my CD+G collections & notice a comma or period will "hang around" while a track is playing, especially on the discs later tracks (10+). I have a Plextor 40x burner & have set the read rate at about 20 & the write rate at 24 (using good quality 24 certified discs).
My question would be: What seems to be the best (max) speed to read & write CD+G discs so as to avoid any small errors like these ? Should I be writing at a lower speed (I did try 12x & got the same little bits of text hanging around).
Thanks - A new MicroStudio user.
PS - I'm backing up my SGB collection.