Add todo for backtest performance

src/Managing.Application/Backtests/BacktestExecutor.cs

@@ -264,6 +264,8 @@ public class BacktestExecutor
             // Run with optimized backtest path (minimize async calls)
             var signalUpdateStart = Stopwatch.GetTimestamp();
             // Convert rolling window to HashSet for TradingBot.UpdateSignals compatibility
+            // NOTE: Recreating HashSet each iteration is necessary to maintain correct enumeration order
+            // Incremental updates break business logic (changes PnL results)
             var fixedCandles = new HashSet<Candle>(rollingWindowCandles);
             await tradingBot.UpdateSignals(fixedCandles, preCalculatedIndicatorValues);
             signalUpdateTotalTime += Stopwatch.GetElapsedTime(signalUpdateStart);