IMHO, there is still a small chance that they could influence some glitches with the sound system, but if in other applications they are not observed, I would have sinned on codecs, MB on network settings.
Although in your case, the version with codecs is also not so probable because you are using x-lite in both systems.
\r
Purely out of curiosity you can even put the priority of the voip application is higher than normal, although this option would help only if the system is heavily loaded.
