svn logtakes a long time when you have recently committed a large number such as 5000 files.
Specifically, this happens when you have path based security. Here’s a link from the subversion documentation that mentions this
All of this path-checking can sometimes be quite expensive, especially in the case of svn log. When retrieving a list revisions, the server looks at every changed path in each revision and checks it for readability. If an unreadable path is discovered, then it’s omitted from the list of the revision’s changed paths (normally seen with the –verbose option), and the whole log message is suppressed. Needless to say, this can be time-consuming on revisions that affect a large number of files
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