For penny pilot issues I was always routed to Emerald but for some reason, lately it was changed to NASDAQOM. This led to costs and commissions creeping up significantly for me. My orders are all adding liquidity. I'm wondering if anyone has encountered a similar issue? https://www.interactivebrokers.com/en/index.php?f=42761&nhf=T
You can select SMART routing options in TWS. For example, "maximize rebates" is one option. But it's likely close to a zero sum game. If rebates are higher then so are fees for liquidity takers and that impacts their actions and prices slightly. You hope they are routing to maximize your interests. It's tough to know without lots of statistical data. Higher fees might maximize your situation if they are getting better pricing on average that more than makes up for it. If you really want to dig into this you can capture NBBO at all exchanges during the nanosecond your fills are executed and then see how they may have routed differently. Although each exchange will route to the best lit bid/offer if they aren't it you will have no idea about dark liquidity. And most liquidity is dark these days. No easy answers. It's only figured out with lots of data and some math.