I'm running Password Safe from git on Fedora 20 x86_64. It often takes a rather long time to start. It waits in pws_os::GetRandomSeed (src/os/linux/rand.cpp) while reading from /dev/random. It seems that even just after checking /proc/sys/kernel/random/entropy_avail the returned amount of entropy is not availlable from /dev/random. (I'm not really sure if that is the expected kernel behaviour.)
It would probably be a good idea to read only as many random bytes as necessary instead of trying to gather as much as possible.