A question for any aerodynamicists out the why does low aero tow speed adversely affect the handling of a glider so drastically?

Occasionally I’ve received an aero tow in my LS-8 (dry) at 55 kt (minimum recommended aero tow speed is 54 kt). The plane is heavy and unresponsive at that speed; it’s an extremely stressful experience! But once off tow the same plane handles like a dream at speeds down into the upper 30 kt range.

Before anyone asks, yes, I do immediately ask the tow pilot for 10 kt more speed - right now! I’d just like to understand what the root aerodynamic cause of the poor handling might be.

-John, Q3