I find my liteon cannot read poor quality discs at high speeds. It also stays at about 12x. The pioneer only has a max 12x read so that result is fine. The blips are nothing imo.
Are you doing any tasks in the background while the TRT is going? It can cause blips and such if you do.
Also, howabout doing a 4x scan again with jitter also enabled? I find that a 4x scan with jitter accompanied by a 16x PIE/PIF scan is more useful than just a 4x scan without jitter. The 16x scan will show how much harder it is for the drive to read the disc with low errors at a high speed.
I've seen crap discs scan well at 4x. If you don't look at the jitter, it can cause you to believe your burn is in spec.