It's custom software because it doesn't need to be a full node, it only needs memo txns. It uses the btcd library, which is another full-node implementation in Go.
Do you know when the problem will be fixed? I'm getting like 10 minute delays on my posts.
Unfortunately I think it will take some time. Hopefully it'll ready for real stress day, 9/1, though. This is what (mini) stress tests are for, to expose these types of issues :)