Anticipated platfrom - scared of "lagging"

Total noob here -

I'm thinking of going with Generic Trade and Firetip. Seem to have done okay on the sims, and I like scalping. This is my intended use.

What questions should I ask to ensure I sign up with someone who has a FAST connection to the market? Is this a valid concern or am I over thinking this?

Thanks in advance for the help!