Depends what you mean by "fast". It seems to have the highest stdout throughput, but that is not necessarily the most important metric: https://danluu.com/term-latency/
Especially true when the methodology to test performance was just `find /usr` [1], and comparing it with a just a few alternatives. I'm sure they have a better and more thorough benchmark these days, but that was pretty funny.
[1]:https://github.com/jwilm/alacritty