If you have hacked ClearSCADA to show the time on the screen, support mentioned you should not show the seconds and I recently had some work on an existing ClearSCADA system and not only do they display seconds but also thousandths of seconds. Should the seconds be removed? I’m guessing it’s a performance thing, forcing all the points on the currently viewable screens to update?
It's going to depend...
a) showing the seconds can be a little misleading, since if the client is connected to the non-Main server they may not see this increment every second.
b) If you have your tag subscribe set to defaults then it's already 1second for most tags, and 0.5seconds for 'Fast' tags. So the data retrieval aspect won't be significant.
c) showing milliseconds doesn't have any real benefit that I can think of... it will still only update the value at the normal / fast rate.. was there any info on why milliseconds were being displayed?
d) the animation load of a seconds thing shouldn't be a big concern.. depending on what you're actually doing with it. I've got some very questionable animations which use the seconds to do psuedo-scrolling text... I wouldn't' recommend that.