I’m not sure it’ll help with that part. If you’ll notice, even when you have it set to show only one block type it can still struggle, even if there are only a couple blocks of that type.
Interestingly, it seems to have no trouble with it when you first enter the builder and it hasn’t finished rendering light and shadows. It’s after it has finished this that it starts giving you those long wait times while it rebuilds and red outlines where you deleted blocks remain.
True, it may require a bit more work but this feature should be a bit more than just the "show blocks of type" functionality. Rather than just ghosting them, that geometry should be fully hidden and not calculated until unhidden.