I am currently using A1 sitemap to build a sitemap for my site. Its quite a big site, but I cannot believe it is so big that it is presently taking over 24 hours to analyse. It has been running for the last 24 hours and is currently sitting at 134000 urls and counting. I am beginning to think something must be wrong here. I don't know whether to stop it and lose all the data, or else persist until god knows when it finishes. 

I have read other similar posts, but I am just looking for some advice, on whether I should perhaps stop the scan now?  I cannot believe there are 134,000 urls on my site 

Most other posts here have been due to configurations or indeed websites that indeed were so big

Anyways, just stop your website scan. (I *always* do the same if I encounter something seems odd.)

You can resume later:
http://www.microsystools.com/products/sitemap-generator/help/sitemap-generator-resume-scan/

Do note that *with default settings* any URLs that were noindex or otherwise through e.g. robots.txt excluded gets removed from the visible results when you stop the scan. (For some websites this can be a very high number of URLs. However, the scanning engine "remembers" all URLs during a website scan, so it know which it has already encountered. This includes e.g. noindex URLs.)

If you have lots of URLs / planning on using stop/resume I highly recommend you check above article. It explains a lot about the different options you can apply.

If you don't see the various options, disable "Simplified easy mode":
http://www.microsystools.com/products/sitemap-generator/help/easy-sitemap-generator-mode/

If you continue to have problems, please email your project to support:
http://www.microsystools.com/home/contact.php