Derek Johnson

Shortcut's project boards used polling with a 5-second refresh interval. When teams of 20+ edited simultaneously, users saw stale data causing duplicate work and merge conflicts. Customer complaints about "laggy boards" were the #1 support ticket category at 340 tickets/month.

Built a WebSocket-based sync engine in Go with operational transforms for conflict resolution. Used Redis Streams for ordered event propagation and PostgreSQL LISTEN/NOTIFY for cross-service coordination. Implemented exponential backoff reconnection and offline queue for network resilience.

Update propagation went from 5 seconds to 38ms P95. "Laggy boards" support tickets dropped from 340/month to 12/month. Supported 200+ concurrent editors on a single board without degradation. Infrastructure cost actually decreased 15% by eliminating polling overhead.

Slack search was slow for workspaces with 100K+ messages. P99 latency was 4.2 seconds and relevance ranking was based solely on recency.

Migrated search index from Elasticsearch to a custom sharding strategy with per-workspace partitioning. Built a hybrid ranking model combining BM25 with engagement signals.

P99 latency dropped to 800ms. Search relevance (measured by click-through on first result) improved from 23% to 41%.