Are you sure you can pass a fractional number to timeout() ?

This LWP::UserAgent::Paranoid has a similar method which accepts fractional values, but their semantics are different: LWP::UserAgent checks that there has been no socket activity for timeout seconds.
You could always double check with wireshark that is effectively so.

Otherwise you can always fork() another process for the HTTP session(s) and avoid freezes (doesn't your GUI framework provides already something similar?)