[mythtv] extremly slow mythfilldatabase in 0.28

[Peter Bennett]

How much memory does your system have, and how much is mythfilldatabase
using? I have found mythfilldatabase using up to 5 GB of resident memory
when processing xmltv files. If your system memory is less than that you
will have swapping, which will slow things down. Use "top" while
mythfilldatabase is running to see memory use and swap file use.