> We already have evidence from history (where trading latencies and intervals were much higher) that the spreads become much higher as trading frequency goes d

> We already have evidence from history (where trading latencies and intervals were much higher) that the spreads become much higher as trading frequency goes down. Would this really hold true linearly across trading frequencies? As we get to shorter and shorter delays, the technological cost for participating in HFT will just keep going up (e.g. building your own microwave transmission towers et. al. sillyness), decreasing the amount of potential participants. Won't this at some point start having the opposite effect - limiting participants in the market to those with enough cash to play? Wouldn't there be some theoretical level of trading delay that should be regulated in order to ensure optimal liquidity as well as market participation?