Higher temp brake fluids prevent the fluid from boiling when the brakes are hot. This is needed on the track, but rarely on the road. Boiling brake fluid is a sudden loss of brakes. The boiled fluid releases bubbles that are easily compressed, causing the brake pedal to drop to the floor.
You are likely experiencing brake fade. New pads would help more than fluid in that case.
This is a good explanation of the difference: https://www.powerstop.com/resources/towing-brake-fade-brake-fluid-boil/
By, "dumping it in", I hope you mean a full brake bleed. You would have to fully replace the fluid in the lines and calipers to have any effect. This can be done manually by pressing the pedal and opening the valve, with a pressure bleeder, or a vaccuum bleeder.