TUI is slow when there are two levels of work item (parent/child)

[SorraTheOrc]

Intake Draft – TUI is slow when there are two levels of work item (parent/child) (WL-0MNWVBYKN009JC7L)

A brief summary: Rendering and interaction in the TUI become significantly slower when parent/child hierarchy is present. We need to identify the bottleneck and improve responsiveness.

Problem statement
When work items include at least two levels (parent and child), the TUI appears to slow down noticeably. This affects navigation and review workflows and can make day-to-day triage inefficient.

Users

• Product managers using the TUI for triage and prioritization.
• Engineers using the TUI for implementation planning and status updates.

Example user story

• As a PM, when I browse a hierarchy of parent/child work items, I want list navigation and item inspection to remain responsive so I can quickly review and update work.

Success criteria

• Parent/child list navigation remains responsive with no perceptible lag in typical usage.
• Expand/collapse and selection updates do not introduce visible pauses.
• Re-render/refresh paths preserve acceptable interaction speed under hierarchical data.
• A regression test or repeatable benchmark demonstrates improvement versus current behavior.

Constraints

• Keep changes localized to TUI performance paths where possible.
• Avoid regressions in filtering, search, and selection behavior.
• Maintain existing UX semantics for hierarchy display.

Existing state

• Issue is observed specifically when hierarchy depth includes parent/child relationships.
• Parent epic context: Slow down investigation (WL-0MNAGHQ33005BVY6).
• No concrete profiling data attached to this child item yet.

Desired change

• Reproduce slowdown in a controlled scenario.
• Profile hot paths (rendering, visible-node building, refresh scheduling, selection updates).
• Implement targeted optimization(s) and validate with tests/benchmark.

Related work

• Slow down investigation (WL-0MNAGHQ33005BVY6) — parent epic.
• Prototype incremental rendering (WL-0MNAL79K20048STX) — relevant performance approach.

Appendix – Clarifying questions & current assumptions

• Q: At approximately how many total items (and children per parent) does slowdown become noticeable?
  • A: Assumed similar to related reports (around a few dozen items), needs confirmation.
• Q: Which user actions are most impacted (scroll, expand/collapse, selection, detail pane updates, auto-refresh)?
  • A: Assumed all list interaction paths, needs confirmation.
• Q: What is the target performance threshold?
  • A: Assumed “no perceptible lag” for normal usage.
• Q: Are there known environments where this is worse (terminal, OS, CI, remote shells)?
  • A: Unknown.