I have no delay, at least after deleting the mp3s i had on the sd while trying out the new tablet. Now it holds only dslr jpegs.
The system media scanner should be the culprit, though it normally should do a full scan only after boot, not after standby. Normally the scanner runs silent, but on my mobile it verboses, it's a two stage affair taking several minutes, with lots of mp3s on the sdcard, and few jpegs. (First stage is searching media, second is scanning media)
Controlling/disabling the scanner requires root. There are apps which bring their own scanner, probably the video and music players of the note, which I disabled.