in reply to Realtime update of a textbuffer from STDOUT/STDERR in Gtk2

Not sure what exactly you mean by "slow and fragmented" (I haven't run your program), but if it's updating in about 1 sec intervals, you could try to reduce the sleep interval of tail, for example to 0.1 sec

-s, --sleep-interval=S with -f, sleep for approximately S seconds (default 1.0) between i +terations.

Just an idea.