You simply shouldn't be day trading bitcoin. The infrastructure isn't in place. The volume isn't there. Massive slippage occurs. When you see tens of millions in USD traded for BTC every minute the story will be different (right now only thousands are traded every minute, very small volume comparing to assets which are actively day traded). The reason the lag is there is because bitcoin has grown a lot in the past few weeks / months, and the correct tech isn't in place to handle this heavy trading that will eventually be normal for bitcoin. At this point in the game, it isn't normal. People who trade stocks often compare bitcoin volume and price behavior to penny stocks (i.e. something that is heavily manipulated).
If you want to day trade there are plenty of other better assets / markets to day trade.
so your basically saying mtgox is not allowing me to day trader. so i didnt know mtgox gets to choose for me what i do with my money.
The lag also is for all users not just day traders. if you think 700 second lag is fine then feel free to keep using mtgox and wonder why your buy/sell orders are costing you money.
As far as expansion goes, im not aruging that more users are coming but most of these issues have existed for months. if mtgox needs months to fix problems I wont be using them. That is like EA saying sorry people who bought simcity we need months before we can put up any new servers.