What is the reason behind those framedrops? (They look worse in person, on the vid they kinda look bearable😭)

P.S. PS3 Super Slim. Played on a 1080p TV with screen settings set on automatic so the PS3 itself is in 1080p but the game changes it to 720p since it's the only res supported by it. When in the settings I remove 1080p and 1080i and lefting only 576p and 720p, framedrops almost dissappear... The game is Ben 10 Cosmic Destruction, disc version. (The same issue happens on other games like Infamous, Sonic Unleashed)