TLDR: I've always used IB's default "Smart-routing" for my orders. Does that end up costing me more in fees? Why does Volume seem to trade at my Limit (to other people) even when I was the first to submit an order at that price, and how can I configure my order routing to ensure my first-in-line priority? --------- 1) Fees: I recently looked into just how much I'm paying in fees and it's not pretty (high 5-figures). 99% of my trading is in Options, and IB's own commission schedule doesn't seem to be the culprit (or at least I'm not sure there's a cheaper alternative than their $0.25-$0.70 / contract), but the exchange fees really add up (sometimes even exceeding IB's trade commission >> aka more than doubling the fee to me.) Each exchange has its own fee schedule (see "Exchange Fees" in page linked to above), some with better maker-taker incentives than others (anecdotally I've noticed the "BOX" ECN fees to be really high). I've never changed IB's default "Smart-Routing" setting, but in the interest of taking the next step in in my options education, is there some routing strategy I can look into that will bring my fees down? 2) Execution: I often observe the maddening phenomenon of putting in the best Bid or Ask (between the displayed spread), and then watching orders go through at my Limit price, except I'm not getting any of them (despite ostensibly being "first in line" at that price.) Someone told me that was due to the fragmented nature of the various options exchanges and that while I may be seeing Volume go through, it may be at other exchanges where my order isn't listed (which I didn't understand; doesn't Smart-routing essentially send my order to all available markets?). He also hinted that no experienced traders use the default "Smart"-routing, which he characterized as a sucker's bet for retail noobs. Is that true? Where can I start learning about how to optimize my routing game? At the end of the day, if a given spread is $0.05 / $0.15, I just want to be sure that if I put in an order at $0.10, I'll be first in line to get filled if someone wants to trade at that price.