Greasy Fork

Problems with the script

I'm recently searching for something that could possibly download books from google and finally find this script. After the test i found that he hangs the browser even in the first selection of downloads when the book is only for preview. I need some help with that.. is some bug?

yes, I have encountered this issue, there are 500+ page can previewed, when
show got 100+ page, but it hangs ..... why ?
Some body can help this ?