The classification in FineReader PDF for Mobile depends on the OS and device. 

For example, a classification process of 800 photos takes 39 seconds on iPhone 11. There were 54 out of 800 photos classified and recognized in 11 seconds. This process depends on the following:

• a device,
• a size of a photo,
• a number of processes working in parallel,
• if the app runs in the background. 

Depending on all factors, the classification can take up to 10 - 30 mins.

You can find more information about the classification in the following articles: 

Classification and recognition in FineReader PDF for Mobile

What types of images are used in classification?

What is the accuracy of the classification in FineReader PDF for Mobile?

How to improve classification search results

Why do I receive such broad search results in classification?