To change NewzScape’s Xover setting, click the Settings Button on the Downloader and then click the Xover/Pause Tab.
NewzScape works by using the Usenet NNTP “Xover” command to ask the server for a batch of post headers. It then runs through the headers and figures out which posts to download. By default, NewzScape will ask the server for 300 posts at a time. You can adjust that number if you think it improves your performance. For example, if you use a lot of keywords to filter out a lot of posts, having NewzScape retrieve more headers will probably make it run faster since there is some overhead involved in asking the server for headers.
If you are re-scanning a newsgroup for some reason, NewzScape will first check to see if a file already exists in the parts folder or the downloads folder, and if so, will skip it. In that case, NewzScape can probably re-scan the group faster with a larger batch size. However, if your Usenet server is well-run and responds quickly, you don’t ever need to worry about this setting.