Parsing 63k items in a 10 MB json string is pretty much a breeze on any modern system, including raspberry pi. I wouldn't even consider json as an anti-pattern with storing that much data if it's going over the wire (compressed with gzip).

Down a little in the article and you'll see one of the real issues:

> But before it’s stored? It checks the entire array, one by one, comparing the hash of the item to see if it’s in the list or not. With ~63k entries that’s (n^2+n)/2 = (63000^2+63000)/2 = 1984531500 checks if my math is right. Most of them useless.