Now that we have 75k tasks and a direct comparison with Bugzilla, it is clear that our Maniphest search doesn't perform at an acceptable level. The fact that such search is powered by Elasticsearch makes this problem more puzzling, because we know that the engine is capable of great results.
Whether this is a Phabricator problem to be resolved upstream, something wrong in our instance, or both, we need to do something about it.
For starters let's attach here specific issues as blocking tasks, so we have a better idea of what kind of problem we have.