Is it possible to bypass warmup?

Sorry, the answer is no.

Like you said you have a 5 minute warm-up time so all the players can connect to the server, but that time is cut short when all players are connected. The timer then switches to a 60 second countdown. The server works in a specific way so by not spawning until the match starts the server would think you are either not connected or you are a spectator. And anyway there is no setting or preference for you to change either.

P.S. Connecting to the server is more of a network speed deal than hardware (though it does contribute). You can have an uber computer and a terrible internet service provider and still be the last one to connect to a server compared to someone on a non-gaming laptop with gigabit internet speeds.