That depends entirely on what you mean by crazy. One of my associates is happily serving DNS for 3,000 domains on a Cobalt RaQ 1. That was not a powerful machine.
It's been my intent in this thread only to correct obvious errors which could lead to a misunderstanding of how DNS operates.
I'll close the thread after pointing out that your TTL can't affect the root servers at all, because they refer to the "glue" a records stored at the gtld servers, and those records always have a time to live of 48 hours.