That is definitely not normal, for comparison I upload an image to my nested environments cloud builder which by the sounds of it would be much slower. The process takes about a minute or less.
I would start by troubleshooting the different factors in your lab.. from the ground up. Network all the way up to the application. See if you can identify the bottleneck. Try moving the appliance to something outside of VMware workstation and see if it makes a difference? Straight onto one of those esxi hosts that you are imaging maybe?
Shashank Mohan
VCIX-NV 2022 | VCP-DCV2019 | CCNP Specialist
https://lab2prod.com.au
LinkedIn https://www.linkedin.com/in/shankmohan/
Twitter @ShankMohan
Author of NSX-T Logical Routing: https://link.springer.com/book/10.1007/978-1-4842-7458-3