Please note that the Pywikipediabot developers have recently done some work to reduce the memory usage. More caching is used as well as the possibility to diskcache large dictionaries on disk instead of memory. I suggest that you enable this cache using "use_diskcache = True" in your user-config.py file.
Diskcache uses the cache directory in the pywikipedia folder. As the home directories are on NFS it may be faster to make a symlink from within your pywikipedia directory to /tmp:
rm -r cache mkdir /tmp/your-username-cache ln -s /tmp/your-username-cache cache
Please do not forget to update to the latest SVN version, especially if you are using interwiki.py
Bryan