"Maybe turn the deflicker off, I heard that slows down the wii... but how long are those load times?(in seconds)"
Deflicker doesn't actually slow down the game or wii. There is just a problem trying to use deflicker on Pal Wiis with the NTSC-J backups that screws up the framerate and speed. It only happens when you first turn deflicker on or off after plugging into a TV on 50Hz.
I get loading times that length on the DVD5 version, so I don't think it has anything to do with the Wii's actual reading of a DL DVD. I reckon its just a natural occurrence given that Brawl doesn't have any real loading screens, runs on a Disc, and is stacked full of content. 4-5 seconds isn't really long enough to seem like a problem too
As for the stuttering, thats probably due to burn quality.