prefetch_related initial attempts

templates/manywallets.html

@@ -9,6 +9,10 @@
 plans and elevations. It also contains scans of centre-line survex output on which
 hand-drawn passage sections are drawn. These hand-drawn passages will eventually be 
 traced to produce Tunnel or Therion drawings and eventually the final complete cave survey.
+
+<!-- This should all be restructured to use .prefetch_related() and .select_related()
+see https://docs.djangoproject.com/en/3.2/ref/models/querysets/#prefetch-related
+-->
 <table width=95%>
 <tr><th>Scans folder</th><th>Files</th><th>Survex blocks</th><th>Cave</th></tr>
 {% for scanswallet in manywallets %}