screen output fails periodically when window is small

[karl anliot]

running ubuntu precise
$ apt-cache policy libvte9
libvte9:
  Installed: 1:0.28.2-3ubuntu1
  Candidate: 1:0.28.2-3ubuntu1

I expect each command I type to output in libvte (. however, the output seems to pause, although it resumes immediately the next time I type something. so even typing a sentence, some keypresses are not reflected to the screen.
also, the output of some commands is hidden. (until the next output)

this problem only occurs when the terminal window is small. when I have the terminal window maximized, it never occurs.

So it's like the post office holding some of my mail, until the next time i get a letter. Like they can't bother delivering every letter, only 95% of them, but they deliver all off them if I get mail delivered at regular intervals.