A common problem is a quick disconnect becomes partially connected causing slow cylinder movement. Try lowering the loader to the ground, turn tractor off, move joystick in all directions to release any trapped pressure. Then uncouple and reconnect each quick disconnect for the curl dump circuit.
By design Cylinders will retract faster than they extend under normal operation. Depending on valve design on your tractor it may have option of regenerative “fast” dump so will dump significantly faster than curl.
