Steps to reproduce:

In Thunderbird libxul.so has exceeded the size of libxul.so in Firefox which makes me believe you're now using all the arsenal of features that Firefox offers. OK. The question is why do I need to have two libxul.so's on my disk without sharing them.

Actual results:

Thunderbird:

-rwxr-xr-x. 1 root root 154481344 Jun 27 23:52 libxul.so

Firefox:

-rwxr-xr-x. 1 root root 149324056 Jun 27 11:52 libxul.so

Expected results:

On a different note I'm not quite sure why Thunderbird needs all of the Firefox features, e.g. WebRender, WebRTC, WebGL, WebAssembly, Service Workers, etc. etc. etc. etc.

This is an email client which is supposed to work with static emails, nothing else. I do understand that e.g. OAuth2 requires you to provide certain HTML features but certainly only a small subset of them.

XULRunner again?
I suppose this is dup. of bug 306324.