It is true that the golems are becoming more powerful, and it is true that it is taking him more time to defeat them. But his greatest enemy is the lack of stamina.
Currently, he had fought and defeated 210 golems. That has been very stressful for him.
He has been pushed to his limit so much that his lungs are currently bellowing in their attempt to restore his stamina. Even his breathing technique can only go so far for him.
He fought 210 enemies in 55 minutes. That's a total of 42 rounds of golems, which has earned him 4,515 points.
In comparison, the person in second place had finished 12 rounds of the golems and earned 390 performance points for their effort.
That is an impressive achievement because at that level of power, the golems would have a total of 33 attribute points, which is three points more than the total attributes of someone at the tenth transformation of the first mortal coil.