On Reddit I encountered a user claiming that implementing Segwit support for an SPV wallet would require supporting an 'additional address chain', but I'm not sure what exactly that entails.

I would expect that the wallet would some additional code in order to recognize the various types of segwit addresses, but I've never heard much talk about this being resource-intensive for the user device. How is it more resource-intensive exactly? How much of an increase is it?

I'm also unsure of how Schnorr would affect this further?

For reference, this is the conversation from Reddit: