As has been posted on in many places and has been reported as a bug, there is a definite computer use lag when the Sims try to do something with a computer. Sometimes it causes a crash also.
I classify this a game breaking bug because the Sims use the computer to do so much. They use it for work performance, university homework, communication, ordering goods, etc. This is so central to their lives that the bug is evident in so many ways. This needs to be fixed soon.
I know there are other problems but many of them have workarounds (although they need to be fixed also).
Just to let you know, I have been in the computer and software field since the late 80s. I consider a bug to be something that is a showstopper as opposed to a glitch. Glitches can usually be worked around. Bugs, however, are usually more severe.
Just my two cents worth.