We’d like to enhance our offering further by removing the in-running bet delay, which is currently set to 1 second.
http://community.betfair.com/horse_raci ... -bet-delay
It wasn't lost on some people that Betfair are probably doing this for their benefit, rather than ours:
We believe this would allow bets to be matched quicker and more frequently, whilst also improving the success rate of Cash Out and our new Auto Cash Out functionality.
I rarely bet In-Play because some of the opportunities I see disappear before the 1 second delay has passed. No delay could make things a bit more interesting.