Fetching an identical revision using the API takes longer when using oldid, since it appears not to use the cache.
Example:
This page loads relatively quickly:
http://en.wikipedia.org/w/api.php?action=parse&page=The%20Beatles
...and produces the following XML output:
<?xml version="1.0"?>
<api>
<parse displaytitle="The Beatles" revid="xxx">
(...etc)
However, taking the same revid, and fetching it using the oldid parameter:
http://en.wikipedia.org/w/api.php?action=parse&oldid=xxx
...takes much longer. (note: replace "xxx" with the latest revision id)
(Priyanka is currently planning to fix this)
Version: 1.16.x
Severity: enhancement