[Zope3-Users] Found a (perhaps obvious) page template speedup

[Jeff Rush]

Perhaps most of you already know this but it bit me this week.  For my project 
I've noticed some sluggish presentation of pages, and a lot of container 
queries flying around for very simple pages.  It turns out to be Javascript 
code (singleBranchTree.xml) that is walking one-level of parents, siblings and 
children for each of my pages, even though I don't have a nav tree widget in 
my skin.

I thought I was doing things the preferred way, by using the existing 
@@standard_macros/page and filling in slots to change out selected portions. 
It turns out that while there is a slot to disable the -display- of the nav 
tree, there isn't one for the page header to disable the -computation- of the 
nav tree, which is triggered from within the browser via navigation_tree.js 
upon the body load event.

It probably doesn't make a noticeable difference when your containers use the 
ZODB and only have a handful of items per folder.  In my case most of my 
containers are SQL tables, with hundreds to thousands of records, so even a 
localized tree traversal results in SQL queries and instantiation of quite a 
few objects.

Besides rolling my own skin from scratch, my solution, since I can't slot it 
out, was to layer the navigation_tree_js with my own, modified copy:

   <browser:page
       for="*"
       name="skin_macros"
       permission="zope.View"
       layer="webaccountant"
       template="template_tablelayout.pt"
       />
<!--      layer="zope.app.rotterdam.rotterdam" -->

and then copy zope/app/rotterdam/template_tablelayout.pt into my project and 
edit it to comment out the line:

   <!--
      <metal:tree use-macro="context/@@standard_macros/navigation_tree_js" />
     -->

It made a world of difference in performance for me.  Your milage may vary.

-Jeff