Long time C# dev here. Both solutions are great so you should all be pleased with what you've achieved thus far. Thank you.
@Antropus for what it's worth LB running with a Mame Set imported via your tool seems perfectly fine speed wise, running an i5 6600, SSD & 16GB. Maybe drive speed is the issue here? I'm also guessing that the XML changes should be minor, but after 15 years in the business I'm not going to assume anything without seeing the code, and as this is a personal project I completely understand that you need to determine when (and if) you're willing to make those changes. Someone else could always pick-up the project for you if real life does get in the way. It could even be integrated into the Launch Box Mame importer @Jason Carr Keep up the good work! I love the frequency of new features and personally haven't seen it cause a negative impact on performance or stability yet.