I don't know what problems you experience. Maybe you can post a short, self-contained example that exhibits the problems?

Personally, I use WWW::Mechanize::Firefox for lots of things without problems.

Thanks Corion.
I followed your advice and I again tried to do what I wanted with WWW :: Mechanize :: Firefox.
Indeed, it is possible to do many things with this module.
For example, I have automatically completed the username and password fields on a form to be authenticated on a site.
It's true that it works pretty well.
However, I encounter the same problem when using the MozRepl module, whith the following error message :
"command timed-out at C:/Perl/site/lib/MozRepl/Client.pm line 186"
First, il means that WWW::Mechanize::Firefox uses MozRepl.
Then, I have to precise that this message isn't displayed every time I run the script.
But, with some pages, it is displayed automatically.
Moreover, in this case, a dialog box displays a message saying that the script https://path_to_script.js seems not to response and asks if you want to stop it.
To resolve this problem, is there a way to change the value of this timeout ?
Or, is it possible to avoid running this script, before the page is loaded ?
Another problem, for pages with a lot of javascript, loading time is sometimes long. How can we improve this?
cf006

There is no convenient way to set the timeout of MozRepl::Client through WWW::Mechanize::Firefox. The least inconvenient way is to set $ENV{MOZREPL_TIMEOUT} before constructing your instance of WWW::Mechanize::Firefox, I guess. The more inconvenient way involves reaching down to

$mech->repl->repl->client->{telnet}->timeout(60)
[download]

This is not pretty, but should allow you to set the timeout.

There is no convenient way with WWW::Mechanize::Firefox to block scripts from loading. Have you looked at an ad blocker?