You're attacking a new business problem. Forces Optimizations have both short and long-term costs. Early optimization runs the risk of high cost with little payback. Postponing optimization until the hot spots can actually be demonstrated is often wise. Fast products produce better customer throughput and delight.
Small products are more deliverable and maintainable.
Products that produce correct results are entirely desirable. Project team focus and morale levels stay elevated. Only those optimizations that are demonstrated to be necessary are actually pursued.