Try www.iqfeed.net it is fast and less than $100 a month
I think you may be going about it the wrong way. Making money inside spreadsheet is not the same as making money in real world. For latency sensitive stuff (arb), you need to find at what latency your strategy breaks and then start looking for providers. You need to account for both market data and execution latency. Unless you figured something no one else could, you will be competing against HFTs and their deep pockets. Why!?what other brokers do you recommend?
Have you ever traded any latency sensitive strategies before? Because it's not a single number that mattersI connect to ib using a VPS with latency about 3ms. The strategy breaks if the latency is larger than 50ms. So, I may have to switch to another broker. Please give some recommendations.
It's not the spread, it's the slippage you care about. Island and Edgex are the top volume exchanges for NASDAQ stocks. With IB, choose SMART route with most volume and it will route where you are most likely to be filled.Do you know for NASDAQ stocks, which exchange generally has the best bid-ask spread? Island, Arca?

Are you assuming aggressive execution on all sides? You might an SOR, that's a low tech solution to that problem, but I'd avoid an SOR provided by a discount broker for obvious reasons.Actually I haven't. I have been trading on paper account. Slippage on futures is OK, but on stocks is very often bad due to large spread, especially during volatile hours. I am not sure how that behaves in real world. Do you know for NASDAQ stocks, which exchange generally has the best bid-ask spread? Island, Arca?