Not at all. Try searching 500/1000 sources (maximum number of conversations any free/premium user can be part of), each with potentially millions of messages, and providing the results in under a second.
AFAIK telegram dont have any super-advanced search features neither it instantly return you results for all these years. Also if you search less common terms it's usually take longer than less than second.
And if you just run client on device without a lot of this history cached search wouldn't be anywhere as fast as you expect. So I pretty sure there no server-side magic there, but instead very good UX.
Also I can tell for certain that with right index grepping tons of JSONs can be very effective on any modern devices.
Can't say there aren't others who've used my search terms, but some things I search for are pretty unique. And I do a lot of searching. And search speed is consistently sub-second. There's no trickery seeing years-old results from VERY heavily used chats appear instantly. There's heavy optimization happening for search, and I'm very certain default e2ee would destroy that experience. Unless you can point to 1 e2ee service working at that scale with comparable UX. I won't even touch on the local aspect as the amount of storage needed to just store the data is waaaay beyond anything I'm even interested in owning, much less the compute to make it so accessible.
