Number of message headers

I have quite slow speed in my dialup connection and it's too long for me to wait until all threads are loaded (I mean threads of second level, with message headers, for example under “General Discussion” and so on). I noticed that maximum 50 or such message headers are downloaded. But only few of them contain new messages. The rest is just the same old threads and I have to download all these headers every time. I would like to ask whether it is possible to reduce the number of generated headers to 20 or even 15 or maybe to make an option in user settings, something like “Show headers with new messages only”. I have to ask because the difference in loading time is quite essential: sections with small number of headers (like “Dutch Lounge” (sorry, Jasper) load five times faster than, say, “General Discussion.”