Sync times have regressed significantly since Ignition launch

[ara4n]

Steps to reproduce

1. Foreground the app in a big account
2. Stare at the sync spinner for 4+ seconds
3. Feel very sad that previously it was syncing in ~1s.

Kegan has dug into a rageshake, and is seeing an inexplicable 3s gap in clientside logs (see rageshake for details). This behaviour started at some point in the last month or so - perhaps when backup got added?

The regression hasn't been picked up by the perftest jig.

Outcome

What did you expect?

Instant sync

What happened instead?

Sync regressing.

Your phone model

No response

Operating system version

No response

Application version

433

Homeserver

No response

Will you send logs?

Yes

[ara4n]

[stefanceriu]

I followed this up on the rageshake and I inspected startup network traffic but there's nothing that points at anything having slowed down client/sdk side. There was a problem in a previous key backup implementation re startup request that but that has since been fixed.
I will close this until we get more data to work with.

[ara4n]

so where is the slowdown coming from in the rageshake? i'm seeing it reliably on every launch.

[stefanceriu]

so where is the slowdown coming from in the rageshake

There were 2 similar rageshakes, I commented on the other one here https://github.com/vector-im/element-x-ios-rageshakes/issues/1074#issuecomment-1810069242

tl;dr; app starts sync -> 2 seconds later sync comes back with 594kiB(!) of data -> takes 1 second to process rust side, app finally gets it

[ara4n]

this is still markedly slower than in sept

[Avi0n]

Seeing ~4 sec here as well. Seems to happen to me when the app has been in the background for a while. Submitted logs referencing this issue.

edit: Today I had a sync that took almost 10 seconds! Submitted another set of logs.

[ara4n]

this has totally changed with the move to SSS. it’s still not as fast as it could be, but it’s faster than it was. element-hq/synapse#17722 might also contribute to perf problems.

keeping this open as it’s still way slower than the original launch.