Its really fast now, thank you.
One small bug:
Its a good idea to offer 'Unkown' in the 'Search all owners' List as a default. But not 'Royal Collection Trust (use if location is unknown)'. I think, you select as default everything that contains an 'unkown'. But it should be equals to 'unkown' (ignoring case).
By the way, i inserted this 'Royal Collection Trust (use if location is unknown)' museum entry, because i had an artwork that i knew it is from the Royal Collection Trust, but i don't know, from which place exactly. So i entered this as fallback-Museum for the Royal Collection Trust. Is this right way to do it?