If you have ever heard people speaking in a language you don't know, you probably thought they talk very fast. And they probably think the same thing about you.
But perception isn't the only measure of a speedy language.
There is also information density. Linguists say a language like Japanese stuffs 12 syllables into each second of talk, but it doesn't convey as much information per second as Vietnamese, for example, which is a slower language, but more information dense. English might often convey the same amount of information in five syllables.
But if you are just talking a lot of syllables, the winners are Japanese, Spanish, and Basque, according to linguist Francois Pellegrino and other researchers. The slowest languages were Cantonese, Vietnamese and Thai.
On the downside, the higher the syllable-per-second rate, the lower the information density. So, with more sound, the less each individual sound might convey.
Some languages are very densely packed with information. According to an example in Atlas Obscura, in the Paamese language of the South Pacific island nation Vanuatu, when a person says "my coconut," they are telling you more than just that they possess said coconut. Depending on which word you use, you might be saying you grew the coconut, you plan on eating it, or use it in some other way. Two words, a lot of information. Kind of fast.
