Sometimes Gantt loads instantly and most of the times (95%) it is unusable to a point I switched to another software. I cannot find any pattern when it loads fast and when slow.

The project I am working on is quite big, but for adding just a simple milestone it takes 30 sec to visualize I added a subtask to a task, then 30 sec to visualize I switch the task to a milestone (which is visualized instantly) but then after confirming the date, 10 sec again loading. It is unusable. I can provide videos if needed.