Recently cracked the implementation using client-device signing through Privy's framework. The key trick here is running a sign message call first to prime the keyshare cache—sounds small, but it makes all the difference. After warming up the system that way, you can push auto-sends from the client side down to around 20ms end-to-end latency (shoutout to infrastructure providers like Helius for enabling this speed). The approach essentially cuts out unnecessary handshakes and lets the cached keyshare handle subsequent operations with minimal overhead. Pretty solid for applications that demand low-latency user interactions on-chain.