I noticed this interesting tidbit in robin's journal about faster calling of XSUBs:
"... if we write it in C, the overhead of calling the XSUB will still be quite heavy. So I'm toying with the idea of building an interface that will allow C routines to be called directly from the optree by the red-hot op dispatcher. I think that's a lot easier than it sounds. It would be nice to integrate it with Inline too. I hope to have a working proof of concept soon."
Sounds excellent, and would be great for the various Perl/XML interfaces which face a massive slowdown due to this overhead.
Go robin, go!