SubversionMergePropertyDiffRenderer is slow

[ebouaziz@…]

The repository has around 40000 revisions, and a lot of mergeinfo on the trunk.

When viewing a changeset that affects mergeinfo on the trunk, it takes 20 seconds to render the changes. render_property_diff() loops on every revision contained in the new mergeinfo property and makes one or more database requests for each (_get_node_revs()), which makes thousands in this case. The displayed information as a result is something like (with links):

trunk 
Property svn:mergeinfo changed
/sandboxes/t6823 (added)	merged: 38954-38956

Note that svn returns the same information in 0.1 second

$ svn diff -c 38957 svn://svn.xxx.yyy/sdk/
(...)
Property changes on: trunk
___________________________________________________________________
Modified: svn:mergeinfo
   Merged /sandboxes/t6823:r38954-38956

Sadly, it seams that the versioncontrol API does not allow to fetch property diffs, only file diffs.

This is with Trac 1.1.2dev and Postgres 9.1