wp_set_object_terms is taking much time in execution

Hi wp developers, i’m working on a automatic import plugin that is almost done, i just need your idea on wp_set_object_terms function that is taking almost half time of complete execution time.

i’m importing posts in loop using csv file, there may be 15K-20K posts in csv. i’m doing this in chunks using loop. my target is to process 120 posts per minute, but wp_set_object_terms taking much time in loop.

so please let me know if any you know anything about this.

Thanks to all.