set half of window on remote lease change

libi2pd/Streaming.cpp

@@ -1439,7 +1439,7 @@ namespace stream
 		m_RTO = INITIAL_RTO;
 		if (m_WindowSize > INITIAL_WINDOW_SIZE)
 		{
-			m_WindowDropTargetSize = INITIAL_WINDOW_SIZE;
+			m_WindowDropTargetSize = std::max (m_WindowSize/2, (float)INITIAL_WINDOW_SIZE);
 			m_IsWinDropped = true;
 		}
 		else

libi2pd/Streaming.h

@@ -58,7 +58,7 @@ namespace stream
 	const int MAX_WINDOW_SIZE = 1024;
 	const double RTT_EWMA_ALPHA = 0.25;
 	const double SLOWRTT_EWMA_ALPHA = 0.125;
-	const double PREV_SPEED_KEEP_TIME_COEFF = 0.1; // 0.1 - 1 // how long will the window size stay around the previous drop level, less is longer
+	const double PREV_SPEED_KEEP_TIME_COEFF = 0.35; // 0.1 - 1 // how long will the window size stay around the previous drop level, less is longer
 	const int MIN_RTO = 20; // in milliseconds
 	const int INITIAL_RTT = 8000; // in milliseconds
 	const int INITIAL_RTO = 9000; // in milliseconds