So, nevermind that last question... Turns out this approach doesn't work really well. Performance is terrible.
I instead started using your RadSpreadStreamProcessing library, but I'm still running into OutOfMemoryExceptions for 100,000+ rows. I'm trying to figure out what the issue is. Do you happen to know if there's a limit to the number of rows you can write to Excel using RadSpreadStreamProcessing? Your demo only goes up to 50K rows, but I haven't seen anything in your documentation that specifies if there's a limit or not.