Any oil used at 50-1 will exibit more residue than one used at 64-1. Think about that. You have more oil in the gas, right? Now, what's the big deal about residue? It's presence indicates that you are using somewhee close to enough oil to lubricate the engine. It also notes that some excess heat is being carried away when the oil exits the engine, and that the contaminates that are created in an engine are being rinsed out of the engine rather than performing multiple cycles up and down the cylinder wall.

When you changed the oil ratio did you re-tune the engine? I'm guessing that you did not since you note that performance appears to be less. Had you re-tuned the engine the performance should have shown a slight increase with the addition of more oil.