Upload high number of suppliers and customers and how will it affect system performance

Hello

We are Facing a new critical challenge of uploading more than 16000 supplier and more than 16000 customers we need to know is that great number of records will affect the system performance or not.

Also need recommendation what is the better solution.

1-Upload 16000 supplier with one supplier site per each

2-Upload one supplier with 16000 supplier site.Same for Customer

In addition do I need to make resizing after upload