Don't bother going through an entire Banzai pipeline for empty text

Merged Robert Speicher requested to merge rs-minor-banzai-perf into master

This bails out of cacheless_render immediately unless the provided text is present, since there's no point.

This should be a slight improvement in our test performance. For example, across the creation of 1,000 Namespace records, which caches the description field and which is blank by default in its factory, this saves about four seconds, which... sure. Why not.

Edited by Robert Speicher