NextBuffer operation takes a long time when there are no rows in a table

We’re trying to get data from a table which contains no rows. The query runs fast, but the SDE gets stuck on NextBuffer command.

Some code that we’re using:

IQueryName2 queryName2 = (IQueryName2)new FeatureQueryNameClass();
queryName2.CopyLocally = false;
queryName2.QueryDef = qDef;  // generated elsewhere
queryName2.PrimaryKey = String.Empty;
IDatasetName datasetName = (IDatasetName)queryName2;
datasetName.WorkspaceName = (IWorkspaceName)((Workspace as IDataset).FullName);
datasetName.Name = "querytable";

// The filter (IQueryFilter) is also generated elsewhere
IName name = (IName)queryName2;
table = (ITable)name.Open();
cursor = table.Search(filter, false);

while ((row = cursor.NextRow()) != null)
{
    ...
}

And the SDE log:

[W 53:22.058] Command:      ExecuteSpatialQuery
[R 53:22.127] Command:      NextBuffer
[W 53:35.625] Command:      CloseStream

Is there any other way to see what’s going on between the client and the server? Or anything else we could do? I’m pretty new to ArcSDE so there might be something siple I don’t know yet.