I have a list of members on a web app and I want to improve usability and performances when users are browsing it. This list can be very long (500+ members). To improve performances, we are implementing pagination with infinite scrolling+lazy loading. We lazy-load the whole list and start filling rows with names and avatars 25 rows at a time.
The problem: the database is designed in a way that I cannot directly load the list in alphabetical order. Sorting would only be possible after the full list is loaded.
This means that while the list is lazyloading users are able to browse it, while they have to wait several seconds before sorting.
I feel that this gap in the user experience could be confusing and unexpected for the users. How would you tackle this problem?