Joomdle coursegrades view very slow to load

Hi, we currently have 33 courses and counting (across 3 categories) and it seems the coursegrades view has slowed down considerably. Last week we had 20+ students trying to open the view and it crashed our server due to excessive workload (our server is not a high-end one unfortunately).

Also, the view displays all courses in one page, regardless of which category it is in. Is there a way to limit the course grades being loaded, or even filter it by categories?

Yes, this view is too heavy for that many courses at once.
You could use User course grades instead, which links to each course grades view.