Hi guys,
Many thanks for your answers. I'll be sure to turn off the update notices in future and stick to checking the changelog before downloading any newer build of the program. And yeah, it's about 69Mb since it's a fresh download of each new version of Calibre from Kovidgoyal's website
And thanks to you acidzebra. Knowing that you can handle 20K titles with minimum performance hit is a great relief. Once more thanks a bundle
Hope Kovigoyal comes up with an intelligent automatic updating feature for any ebook downloaded, on his Calibre soon
Best Regards. seraph7