Performance tricks in Gmail you should notice

1. It’s not infinite scroll. It’s limited.

2. A normal inbox screen shows 50 items. Folders/labels show this too – they are statically generated groups not dynamic

3. If you search, you see 20 results

4. The “count” on matches is partial like “1-20 of 37 results” which on the next page becomes “21-40 of about 74 results” – because they give you the first matches fast and worry about how many older ones are in there later

5. You don’t get a ton in the inbox view – name, subject, a little preview – this is stored preview material

6. It really is super fast in the UI. I suspect a ton of it is stored locally for things like Next or refresh