End portals and end gateways cause abnormal amounts of lag since 21w11a

End portals and end gateways cause serious lag that doesn't happen in 1.16.5, even if there is only one block. This lag seems to be dependent on how much the end portal/gateway takes up your screen. When looking at the end gateway in 1.16.5, I get 58 FPS, but in 21w11a, I get 8 FPS and can barely move.