Hello,
I have tried both Labeling Tool https://learn.microsoft.com/en-us/azure/cognitive-services/form-recognizer/quickstarts/client-library?tabs=preview%2Cv2-1&pivots=programming-language-rest-api#train-a-custom-model and RESTful API https://learn.microsoft.com/en-us/azure/cognitive-services/form-recognizer/quickstarts/client-library?tabs=preview%2Cv2-1&pivots=programming-language-rest-api#train-a-custom-model with 2 page PDF. The performance of them are around 1 min.
If you feel that is slow, please let me know which way you are using and the sample document if not confidential.
Regards,
Yutong