Mariokart 64 slowly first 15 sec. before karts starts on mupen core

Hi, I try the new version of mupen and parallel on shield tv android and it’s work good. I just notice a strange behaviour on mario kart 64, the first 15 seconds of the start game is slowly before karts start the course and after work good. I have vulkan driver and rewind and v-sync disabled. test the usa and pal rom and it’s the same. have you experienced the same behaviour ? thanks