We have been doing some testing using the Silverlight map in a degraded network environment and found that when running on a network with higher latency and lower bandwidth, eg 512k or worse (eg cellular data networks), the map definitely preforms poorly. This is expected, however, I was looking for ways to potentially improve performance when running on a degraded network.
I am looking for any ideas that might help.
One thing that occurred to me was a way to have layers persistently client side cash tiles, which would help improve performance over time.
Are you using feature layers? Are you disabling clientside cache (ie layer.DisableClientCache=true). Those are both things you should be on the lookout for. If you need feature layers, try and limit the use, limit the number of attributes you request, and use OnDemand mode and scale dependency to limit how much and how often these layers are used, since they can transfer quite a lot of data.