Hello Emmanuel,
I understand that in a traditional way you want an email with such issues. But I think its important to embrace the forum as an arena for shedding light to potential issues like this. Maybe I`m the only one who bothers with this, or maybe there is other users also experiencing the same things, and thus its easier for them to contribute into this or similar types of posts on their experiences as well.
I`m sorry I didnt have time do to a perfect repeated testing scenario of these things yet, I will test more as i get to spend more time with bubble.
Here is a screenrecording of one testing scenario I did just now:
http://recordit.co/TnfY9tdUpJ
I have a 20Mbit connection in a developed country so the connection capacity should not be an issue. I have tried with two different connections today and same issue. Last connection tested with on screenrecording above had the following spec tested on speedtest.net (19mb down / 17mb up).
To me it seems that some stuff served via cloudfront has a huge delay. (Time to first byte)
On some images I see 755ms to first byte.
To solve bandwidth problems where one is awaiting ajax data, you could implement a request timer that shows a message when things take longer than expected. Gmail handles this in a great way.
Some suggestions for approaches on slow requests:
Offline.js - http://github.hubspot.com/offline/docs/welcome/
Firebase-on-error (can detect slow writes, errors etc. AFAIK write operations only) https://github.com/pkaminski/firebase-on-error
Or just custom written JS code, if request not fulfilled within X (4?) seconds, display user warning on frontend. (The request is taking a bit longer.)