Measuring your own data gaps
A simple diagnostic that has been worth more to me than most analysis: count the gaps.
For each session, record how many times the stream went quiet for longer than it should have, and how long. Then compare bad trading days against gap frequency. If they correlate, some portion of what you've been calling strategy performance is actually connectivity.
It's a boring measurement and it reframes arguments. "My strategy struggles when things get busy" and "my connection struggles when things get busy" look the same in the equity curve, and only one of them is fixed by touching the strategy.