This is not a homework ;) I need to both A) optimize the following code (between a TODO and a ~TODO) and B) convert it to [P]Linq. Better readability is desired. It might make sense to provide answers to A) and B) separately. Thanks!

lock (Status.LockObj)
{
    // TODO: find a better way to merge these dictionaries
    foreach (KeyValuePair<Guid, Message> sInstance in newSInstanceDictionary)
    {
        this.sInstanceDictionary.Add(sInstance.Key, sInstance.Value);
    }

    foreach (KeyValuePair<Guid, Message> sOperation in newSOperationDictionary)
    {
        this.sOperationDictionary.Add(sOperation.Key, sOperation.Value);
    }
    // ~TODO
}