The size of the production or source environment is partly responsible for the speed of any migration.
Design, store settings, brands, categories, etc., are moved within seconds, but more oversized items like orders can consume significantly longer time. Anonymising data will further slow down the process due to the extra steps involved.
While the whole point of a staging environment is to match as close as possible to the production version, there are cases where copying all your orders to make a design change on your homepage is complete overkill. Before creating a new environment, think about what you are moving to and why.