I need to bind 60 thousand-ish rows to an ultrawebgrid and I cannot find a configuration that gives me acceptable performance. 

I'm using an ObjectDataSource returning a DataSet, caching is enabled.  The grid has paging enabled, filtering via a filter-row, and sorting enabled.  Of course the initial load from the database will be slow...that doesn't worry me.  The time it takes to re-sort the list, filter, page, etc, is all 30+ seconds.  CPU is pegged the entire time.  Anyone know what's going on?  It's not hitting the database, these records are in memory, it should be screaming fast.  I've thrown every switch I can find in the grid and in the ObjectDataSource to find & fix this bottleneck, but no luck. 

Any suggestions out there for best-practices when dealing with medium-large records sets?  I've considered dealing with business objects rather than a DataSet, but that seems to make filtering and sorting stuff much more difficult. 

Thanks!
Walter