JSOP - big swinger throwing 10 million shares around at a time. LOL. According to the TOS 606 report, they are getting paid .0035 cents per share for order flow from Direct edge and .0022 by the likes of Citadel and Citi. How much of that are you getting back? Yep, you are surely saving big bucks on that size you're throwing around.
https://www.thinkorswim.com/tos/client/complianceWorld/orderRoutingReports/AMTD-2055-0414.pdf
BTW, here's a hint before you mention you only place limit orders etc etc... Via IB if you direct a liquidity providing order to a number of exchanges, you get the exchange rebate and can obtain negative commissions.
https://www.thinkorswim.com/tos/client/complianceWorld/orderRoutingReports/AMTD-2055-0414.pdf
BTW, here's a hint before you mention you only place limit orders etc etc... Via IB if you direct a liquidity providing order to a number of exchanges, you get the exchange rebate and can obtain negative commissions.