GB with the stock launcher is pretty terrible at least it is on my DX. Rooted, overclocked to 1.35, ads disabled, 100mb ram kept free and LauncherPro and it is decent. Still nowhere near as fast as my Epic is tho.
If I was staying with the DX I would for sure be going back to .340 and Apex until Apex for GB came out or maybe try Liberty GB but apparently it is still buggy.
As for your answer, we are really not suppossed to be posting ANY links to SBF files on this forum. If you want that sort of thing, head on over to mydroidworld. It takes literally 5 minutes to go back from GB to Froyo once you get everything installed.