[Bug] The GUI slows in proportion to the amount of visible tasks, so solely load visible tasks.

Steps to reproduce

1. Load a task list, like wim.nl.tab.digital/apps/tasks/#/collections/all's.

2. • Modify a task and wait for it to update.

   • Sometimes, scrolling can be slow, too.

Expected behavior

The tasks should be dynamically loaded as they are viewed.

Actual behaviour

All of the tasks are preloaded at initialization time. This makes it hideously slow when many tasks exist.

Tasks app version

Unfortunately, help.nextcloud.com/t/97847/5 + | grep 'tasks' doesn't return anything.

CalDAV-clients used

sourcePackage=org.tasks
versionName=13.6
versionCode=130605

Browser

Name         : firefox
Version      : 120.0
Release      : 1-1.1
Architecture : x86_64
Source RPM   : firefox-120.0-1-1.1.src.rpm

Client operating system

NAME="openSUSE Tumbleweed"
VERSION_ID="20231218"

Server operating system

404 pages report:

(Ubuntu)

Web server

404 pages report:

nginx/1.18.0

Nextcloud version

25.0.8.2, per scan.nextcloud.com/results/e9c6cb22-1bf8-424a-9aec-2ba3ce521bac).

Updated from an older installed version or fresh install

Updated from an older version

List of activated apps

1. dashboard

2. files

3. photos

4. activity

5. spreed

6. mail

7. contacts

8. calendar

9. notes

10. deck

11. tasks

Browser log

Available at gist.github.com/RokeJulianLockhart/c99f881a03aa9f60e97457be1837802b.

Additional info

tasks/releases/tag/13.6 reports 1 074. However, the server shan't inform me of exactly how many, due to issues/2416#issue-2051445539.

Start by reproducing the slowdown with a large task collection and review the linked browser log. Trace the initialization and scrolling behavior in the Tasks GUI; done means only tasks currently viewed are loaded while updates and scrolling remain responsive.