If you are indeed talking about vanilla netsend and netreceive, the poll function is called during pd's main loop, not when something arrives at the socket. In x_net.c : sys_addpollfn(sockfd, (t_fdpollfn)socketreceiver_read, y); socketreceiver_read is in s_inter.c: void socketreceiver_read(t_socketreceiver *x, int fd) sys_addpollfunction schedules the function to be called each pass through Pd's main loop.
Martin
If that is the case, then it seems the bug lies elsewhere but is there nonetheless. The clock_delay workaround has fixed this in pd-l2ork permanently and I am yet to experience gui freeze that has been plaguing our setup way too often before the said workaround.