IPNS uses the IPFS kademlia DHT, which has some performance problems that you can argue are fundamental.
For solving a similar problem with iroh, we would use the bittorrent mainline DHT, which is the largest DHT in existence and has stood the test of time - it still exists despite lots of powerful entities wanting it to go away.
It also generally has very good performance and a very minimalist design.
There is a rust crate to interact with the mainline DHT, https://crates.io/crates/mainline , and a more high level idea to use DHTs as a kind of p2p DNS, https://github.com/nuhvi/pkarr
It would be possible to add a layer on top of IPFS to include some context with every hash lookup so the search can be more focused, but the original design just assumed it was ok to do a log2 search for every chunk.
Using it to publish every tiny chunk of a large file is a horrible idea. It leads to overwhelming traffic.
If you publish a few TB of data, due to the randomness of the DHT xor metric you have to basically talk to every node on the network. Add to that the fact that establishing a tcp libp2p connection is much more heavyweight than sending a single UDP packet like in the bittorrent mainline DHT, and you are basically screwed.
In iroh we don't publish at all by default. But if you have to use a DHT, the fact that we have a single hash for arbitrary large files due to blake3 verified streaming helps a lot.
You still get verified range access.