Demo vs Live Execution

Demo and live accounts run different execution paths, and the difference is a design fact rather than a defect. A demo fills against the price feed with no counterparty, so it never requotes, rarely slips and always fills the whole order at the quote on screen. A live account routes to a dealer or a liquidity pool, where the size available at that quote is finite and network latency is real. The consequence is that a strategy validated on demo can lose its edge in its first live week with nothing changed except the fills. The gap is widest exactly where it hurts: at the news release, at the session open, and on any order large enough to consume more than the top of the book. Running the same setups live at minimum size for a few weeks, and comparing the fills, is the only honest calibration.