LINQ
return databaseMapping.EntityContainerMappings
                        .SelectMany(ecm => ecm.EntitySetMappings)
                        .SelectMany(esm => esm.EntityTypeMappings)
                        .Where(etm => etm.MappingFragments.Any(tmf => tmf.Table == toTable))
                        .Select(etm => etm.EntityType);

VS this

// PERF: this code written this way since it's part of a hotpath, consider its performance when refactoring. See codeplex #2298.
var types = new List<EntityType>();
var entityContainerMappings = databaseMapping.EntityContainerMappings;
// ReSharper disable ForCanBeConvertedToForeach
for (var entityContainerMappingsIterator = 0;
    entityContainerMappingsIterator < entityContainerMappings.Count;
    ++entityContainerMappingsIterator)
{
    var entitySetMappings = entityContainerMappings[entityContainerMappingsIterator].EntitySetMappings.ToList();
    for (var entitySetMappingsIterator = 0;
        entitySetMappingsIterator < entitySetMappings.Count;
        ++entitySetMappingsIterator)
    {
        var entityTypeMappings = entitySetMappings[entitySetMappingsIterator].EntityTypeMappings;
        for (var entityTypeMappingsIterator = 0;
            entityTypeMappingsIterator < entityTypeMappings.Count;
            ++entityTypeMappingsIterator)
        {
            var entityTypeMapping = entityTypeMappings[entityTypeMappingsIterator];
            // ReSharper disable once LoopCanBeConvertedToQuery
            for (var mappingFragmentsIterator = 0;
                mappingFragmentsIterator < entityTypeMapping.MappingFragments.Count;
                ++mappingFragmentsIterator)
            {
                if (entityTypeMapping.MappingFragments[mappingFragmentsIterator].Table == toTable)
                {
                    types.Add(entityTypeMapping.EntityType);
                    break;
                }
            }
        }
    }
}
// ReSharper restore ForCanBeConvertedToForeach
return types;