GTA4 and the Framerate

So, recently i played GTA4 and 5 again on my 360 and i was shocked how much framedrops GTA4 has and 5 not. But why is that so? Isnt GTA5 not more intensive for the 360 than 4? I dont have those massive drops with GTA5? It feels like the Xbox can handle GTA 5 way better than 4