Performance issue: session-child-cycle becomes extremely slow with many sessions

[zenyr]

Description

session-child-cycle (ctrl+right) and session-child-cycle-reverse (ctrl+left) become extremely slow in workspaces with many sessions (e.g., after subagents create child sessions). Response time exceeds 10 seconds, causing input lag and ignored commands.

Root cause: `Session.children()` in `packages/opencode/src/session/index.ts` performs O(N) scan of all sessions via `Storage.list()` and `Storage.read()` per cycle.

OpenCode version

0.15.23 (sessions persist across versions)

Steps to reproduce

1. Create workspace with 500+ sessions (e.g., run complex tasks with subagents).
2. Press ctrl+right or ctrl+left to cycle sessions.
3. Observe delay in switching.

Screenshot and/or share link

... no wonder 😅

Operating System

macOS (Darwin)

Terminal

No response

[rekram1-node]

good to know thx

[ry2009]

Should more then resolve the problem but open to comments or concerns: https://github.com/ry2009/opencode/pull/4

[zenyr]

Guys please add input about your recent experience with this issue, since I myself have not suffered this issue these days.

• Before: took >20s every time
• After: takes <2s (not an exact science)

For the record

now my storage looks like this after extensive use of OC:

• No gigantic /session folder anymore! 👍 Huge W
• No, the switch is not INSTANT fast yet. But it works within reasonable time nonetheless.

So... of course, this could be even better with more optimizations. But I consider this mostly solved.

[ry2009]

@zenyr is this what you found naturally with the newest OpenCode version?

[rekram1-node]

I did do a small optimization for subagent stuff in terms of perf that could be what fixed it

also we are improving the ux of subagent nav soon

[ry2009]

Should I close out my perf with extra caches fix then? @rekram1-node