Switching lands where you clicked, and the link holds
Clicking two sessions quickly lands on the one you picked last, a slow window no longer holds up the engine, and a big reply no longer drops the link.
When you clicked one session and then another right away, the two requests could be handled out of order and leave you on the one you meant to leave. Opening a session, sending and steering now apply in the order you did them, while Stop still goes through at once.
A window that was slow to read could hold up the engine's other work while it waited. The engine now gives up on a stuck window after two seconds without progress instead of stalling, and it no longer holds its main lock while it does slow work.
A reply too large for the window's buffer now fails just that request instead of dropping the whole connection, which was one cause of the Reconnecting message.