PDF.js overloads CPU when opening large PDFs on higher security slider levels
When downloading a large PDF, such as https://www.alchemistowl.org/pocorgtfo/pocorgtfo08.pdf , other tabs failed to render, open, or close correctly.
- tabs would be slow to load,
- the visible area would be rendered, but scrolling outside the visible area would show white space,
- closing tabs by clicking the x in the tab header would sometimes work particularly if I held the trackpad down for a while. But a quick click would often fail to close tabs.
I think this is new behaviour in Tor Browser 7.0.1 in high security mode on macOS 10.12.5. (I have done similar things in the 6.0 series, and it was ok.)
This is reproducible in high security mode. The only issues reproducible in low security mode are:
- tabs would be slow to load, which I believe to be an expected behabviour when downloading a large file over the same guard connection.
It does not happen in Firefox 54.0.