if you make a game based around building things using a large catalogue of stuff, and you add custom content support for modding, for feck's sake please parallelise the content loader so it can utilise multiple cores and parallel SSD reads.
there's always going to be a group of players that loads up gigabytes and gigabytes of mod content, and you're relegating them to watching the loading screen tick along for 30 minutes while you process thousands of content packs sequentially.