MY FPS ALWAYS DROP AFTER FINISH THE 1ST HALF

At 1st half, the game running properly and smooth, but when the 1st half finish, my FPS will drop below 10 and the hell am I going to play with that fps, my laptop is ASUS TUF A15 which already surpass the optimum requirement which my GPU is nvidia rtx 3050. The problem always occur after the 1st half finish.