Bugzilla

This is very strange, in particular a 650MB favicons.sqlite is very unexpected, it seems to be 10 times bigger than expected. That seems to point out to some kind of file corruption, and such a large size, depending on the PC specs, may also explain why it hangs and uses so much cpu.

copying just favicons.sqlite (without place.sqlite) to a new profile will likely just discard most entries because they won't have a match in places.sqlite. That would  explain why then it works, removing orphans is easier and cheaper.

Now the problem is understanding what is taking space into that database... Do you still have a copy of the corrupt favicons.sqlite to analyze?
Could you check it with this tool https://www.sqlite.org/sqlanalyze.html and post results here?

I may also ask you to run some queries to better understand what happens, I wonder mostly if this is effectively corruptio or if somehow a site was able to store thousands (or a few) oversized icons.

This is very strange, in particular a 650MB favicons.sqlite is very unexpected, it seems to be 10 times bigger than expected. That seems to point out to some kind of file corruption, and such a large size, depending on the PC specs, may also explain why it hangs and uses so much cpu.

copying just favicons.sqlite (without place.sqlite) to a new profile will likely just discard most entries because they won't have a match in places.sqlite. That would  explain why then it works, removing orphans is easier and cheaper.

Now the problem is understanding what is taking space into that database... Do you still have a copy of the corrupt favicons.sqlite to analyze?
Could you check it with this tool https://www.sqlite.org/sqlanalyze.html and post results here?

I may also ask you to run some queries to better understand what happens, I wonder mostly if this is effectively corruption or if somehow a site was able to store thousands (or a few) oversized icons.