I meant:
```
foreach (var sceneMappings in mappings.GroupBy(x => x.TvdbId))
{
    _findbytvdbIdCache.Set(sceneMappings.Key, sceneMappings.ToList());
}
```

That way you hit the database once (at the repository.All() at the start of this method).
You could actually remove the SceneMappingRepository.Findbytvdbid method since it wouldn't be used anymore.