One of our complaints from traders: the UI optimised orders for speed, not correctness. Some flows updated positions before the exchange responded, then corrected them later if the order was partially filled or failed, but this caused late updates, incorrect states, and failed sells. Now that our indexing and data API is much more performant, we changed this so that market buys and sells wait for the trade response; fills, partial fills, rejections and errors show immediately. This also improves correctness and sell success rate, making it safer and better to trade.