I’ve tested it and it seemed to fix the issue, but the problem seems to be more related to the upload than the block-unblock.js. With (or without) removing the code the page freezes on other parts of the page. After testing a while, to understand why this happens not in all parts of the page, it seems that it has something to do with the use of jQuery. Whenever jQuery is used after the upload (even when it’s not directly after), the page freezes.