This might help others using MSSQL 2008.
(Our problems revolved around very slow snapping, measure tool and any queries)
The SQL Spatial types have impaired our performance greatly. When running the same problematic features as SDEBinary, in the same Dataset, our performance issues are gone. Is this a fix for all using MSSQL 2008? I can't say that for sure, but it definitely has made a big difference on our data.
If you are running a similar setup. Simply copy and paste a feature into the same Dataset, and change the keyword to SDEBinary. If you don't see SDEBinary, you may be setup where the Binary option is your default. You could check DBTune to see the default "GEOMETRY_STORAGE", ours is set to "GEOMETRY".
Good luck.