I think secret tunnels would be really cool anyway. Especially if you could build them between friends houses. Not super functional or efficient, but pretty cool none the less.
-1 If lag is the main argument for this , its unlikely this would cause any less lag, also wanting a feature added when lag is the issue in the first place is more than a bit odd, one should be asking for less features not more. Aside from being a passage way, this wouldnt function in any other way, time would be better spent on other things.