How to handle long lists
It depends if all tasks on the list are still relevant or not. Review your tasks (possibly using the built-in Review old tasks or Eisenhower method workflows) and remove what's no longer needed. Perhaps something can be delegated to other people and moved to Waiting?
If you had the task in the list for months and did not touch it, consider deleting it. You should not put everything you can possibly think of in Lunatask just because it might be useful in the future. Does it still make sense to track it? Remember, if something is important, it will come back one way or another.
If you still have 80 relevant tasks in your backlog, then you have 80 tasks in your backlog. There's no way around it, and that's okay. The important part is using the various sections and priorities cleverly to you know what is first, what is after that, and what is later – 80 tasks is backlog is okay, 80 tasks to work on now is not. Planning only a small number of tasks at a time, you can give a solid structure to your long task list. Plus, given that your backlog is always sorted by our prioritization framework as well, there's already some structure in it by default.
Also, don't forget to hide tasks that are not actionable at the moment out of sight. In Lunatask, you rarely want to have all tasks in the list shown at the same time unless you're in the process of reviewing and cleaning up your task list. Most of the time, you'll want to have your Waiting and Later sections collapsed while working.
To collapse any section, double-click its name – this works for all sections in all workflows.