The oddity here is English, not the languages spoken in India. It’s easy to show it by comparing vowel duration in a few languages:

• Telugu (Dravidian) - short vowels are 70~90ms, long vowels 180~195ms
• Hindi (Indo-European) - vowels are 100~180ms long
• Spanish (Indo-European) - vowels are 130~150ms long (NB: I’m analysing the data for native speakers)
• Japanese (Japonic) - tables IV-V show some data for a short /a/, 70~112ms. I’d expect the long vowels to be thus around 140~220ms, if simply doubling it (Japanese is mostly moraic after all, and open vowels tend to be longer)
• English (Indo-European) - 85~420ms

So yes, your typical language spoken in India is spoken faster than English. That doesn’t say much because probably most languages are spoken faster than English.

Also, keep in mind that “Indian languages” isn’t that useful of a label. It’s a lot like lumping together Basque, Italian, Russian, Hungarian and Maltese as “European languages” - sure, it can be done, but odds are that you won’t get any meaningful conclusion out of it, you know?

English (for various reasons) is kinda the only common language throughout India. There isn’t actually one non-English language that you can learn and be understood throughout ALL of India, (e.g. if someone from the state of Punjab goes to the state of Tamil Nadu, they likely might need to speak English to understand each other though there are always exceptions to this) so English is very commonly spoken throughout India. As with any English speaking country, the language has changed within India and Southeast Asia over time (there is regional slang/expressions/colloquialisms unique to SE Asia like calling the ‘truck’ or ‘boot’ of a car the ‘dickie/dicky’). Many of the other languages spoken throughout India are more strict in their phonetics, e.g. each syllable has a specific sound and doesn’t change based on the surrounding syllables. Many English speakers who learn in India likely end up using this kind of speech pattern with English as well, leading to a different cadence in pronunciation than in other regions of the world. There are times it sounds faster, but pay attention and see if you can notice if the person speaking is using more syllables or pronouncing parts of the word you might skip over in the same word, but just faster.

I think there’s a vast difference in south India and north India. South Indians tend to speak a lot faster.

I work in maritime, often alongside Indian counterparts who speak both English to me and Indian to their ship mates.

Yes, they do speak Indian just as fast. Yes, the way they speak English has a lot to do with the cadence of how they speak their native language.

As far as the flow goes, I’ve noticed that Indian does flow better than English just listening to it, but I don’t know enough of it to make that observation with any credibility.