KB00022803 Choosing a News Collection Method
NEWNEWS is definitely the best, if the server supports it. It is both fast to execute on the server, and supplies the least data.
XOVER and XHDR are similar, but :-
XOVER is almost always faster to _execute_ on the server, but it generates far more data (most of which is ignored by the Post Server).
XHDR is slower, but produces far less data
Therefore, if you are on a LAN (where latency is more of an issue than bandwidth), then XOVER is probably better. However, for modem users (where bandwidth is more important) then XHDR is probably better. Note also that you can always overcome the latency problem with XHDR by using multiple parallel connections. This is a good idea anyway as there will always be some latency with news servers.
GROUP is the fastest (even more so than NEWNEWS), but can result in duplicated downloads, and can also skip some messages.
You can switch between the options at any time, but the Post Server may require quite a long time during the first connections to catchup.
When using the GROUP option, the 'Ignore articles older than...' has no effect.
The NEWNEWS option is based upon the last collection date, whereas the others are based upon the last article number. Therefore, switching from NEWNEWS to any other option will require additional time during the first collections to catch up.