If you're not using AMD, this delay should be very minimal. It cannot be done away with altogether (a flaw shared by all dialers I've ever worked with), but can be minimized by tweaking your campaign settings according to your list quality and campaign parameters. Basically you want to make sure you always have an agent available. As far as networking is concerned, I doubt you could do much on that level to improve the delay. Maybe shave off a few milliseconds of latency? Nothing significant.
Keep in mind, the system has some serious data crunching to do when making the decision to pass a call to an agent. Look up channel data, see who's available, determine who's the most appropriate amongst those, etc... Unless you're hiding a quantum processor and associated coding libraries in your closet, it won't ever be perfect
Any improvements to this delay would likely happen at that level, improving the code and making it more efficient.
Another thing to keep in mind, if list penetration is your main KPI or if you have a really tight target, preview dialing will always be the way to go. Predictive dialers are at their best in quantity over quality type scenarios because that half second of silence is a dead giveaway that your agent is in a call center. That's just how things are, can't be helped.