Compyle's initial architecture for remote dev sandboxes suffered from 30-second startup times and over 200ms terminal lag, making the user experience feel sluggish. The culprit was a middleman socket server that added network hops for authorization, billing, and routing, creating a painful bottleneck for real-time coding.

To fix this, they implemented a warm pool to eliminate cold starts, slashing startup to 50ms. The bigger win came from cutting out the middleman entirely, using JWTs for direct client-to-machine connections. They leveraged Fly.io's fly replay proxying to route requests, moving persistence and billing logic out of the hot path.

The final step was a multi-regional pool, placing servers closer to users worldwide. This reduced terminal roundtrip latency from over 200ms to a median of 14ms. The lesson is architectural: removing the socket server's complexity was more impactful than adding infrastructure, proving that simpler solutions often deliver the biggest performance gains.