If the /tic setting is any correlation to other game engine settings, it's in reference to the processing of a 'frame' of data. A ticrate of 30 would mean the server processes 30 seperate frames of data, taking from the input buffer, and crunching that data, spitting it out to clients in the form of a frame, rinse and repeat.
The drawbacks to high framerates are obvious - increased CPU load, and the possibility the timing of other functions will be disrupted due to changing the default rate.
There's also an issue that if the buffer can't be emptied, some data sits and waits for the next frame. If the rate is too low, there will be a constant lag effect, beyond ping. You could also run the rate too high, where there isn't any data in the buffer, yet a frame is still pushed to clients, which is wasted bandwidth.
Until we get some explanations as to what it is, and what we can do with it, I'd not suggest screwing too much with it. We need some developer interaction here rather than speculative answers.
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