Caching ResourceManager lookups?

[Ron]

Is it any faster to cache lookups to the ResourceManager:

private static string GetLocalizedString(string key)
{
string localizedString = (string)localizedStringCache[key];
if (localizedString == null)
{
  localizedString[key] = _resourceManager.GetString(key);
}
return localizedString;
}

[Tim Gebhardt]

I ran some tests and it doesn't look like it's any faster.  Two things:

1) The code for the caching may need to be thread safe, and that might actually slow that function down since ResourceManager.GetString already is.

2) I looked at the GetString method with Lutz's Reflector and it's just doing a Hashtable lookup in that method anyway.