At the top of the page where you add a taxonomy queue (the Smart Queue Taxonomy module needs to be enabled for this), there's the following:

(...) Using this with large or too many taxonomies may degrade performance.

What (number) is meant by 'large' or 'too many'? Did people experience problems with this? If so, at how many vocabularies/terms?

Comments

For a single vocabulary, I don't think the size matters much.

If you select multiple vocabularies, it has to process all of the possible combinations of terms, so thousands of terms could start to have a performance impact on your site. I would recommend not doing this.

I didn't do any benchmarks so I don't have specific numbers; I threw in the warning because, at the time I wrote it, it seemed like a good idea to let people know that doing something like combining two taxonomies each with a thousand terms (which leads to a million unique combinations) could really create lots of subqueue data.

Status:Active» Closed (fixed)

Yep, makes sense :) Thanks for explaining.

Maybe this would be a good thing to add to the documentation?

Title:Taxonomy node queue performanceDocument Taxonomy node queue performance
Component:Miscellaneous» Documentation
Assigned:Unassigned» ezra-g
Category:support» task
Status:Closed (fixed)» Active

I'll quote Merlin's answer to this question in the documentation.

Status:Active» Fixed

This is now added to the documentation.

Status:Fixed» Closed (fixed)

Automatically closed -- issue fixed for 2 weeks with no activity.