100 witnesses would require too much much work for an individual to investigate about each witness and determinate if he can be trusted or not.
the more witnesses - the slower the network, the speed of the txs is the main reason to build the network with (
limited amount of) trusted nodes/witnesses
If we have fast CPU or network connection, is that a problem. I heard Dash has many more than 12 nodes (witness?)
Yes, unlimited amount of masternodes

But I'm sure Byteball is much faster than Dash, I mean theoretical limits of the underlying technology.
We could ask the dev about the matter to get the answer from the most authoritative source
Tony will not comment, I think -
this would contradict his principles
Tony makes no comparisons, no hypotheses, and does not make any marketing promises.
He can not do this because he is, of course, biased or not objective (Speculation is allowed to everyone but not to the Creator).
He is (or was) more or less a scientist (Scientists are disgusted with marketing and any kind of non-objectivity).
In this context, silence is the highest (and hardest) art.
Byteball is what it is, the rest you have to fill with your own knowledge / imagination.
However, the topic of performance has already been dealt with generally:
https://bitcointalk.org/index.php?topic=1608859.msg17788906#msg17788906 ff.