[Due for payment 2025-06-12] [$250] Optimize useLoadReportActions performance for large sets

[gedu]

Proposal

Optimize reportActions loading performance for large sets

Problem

When users have chat histories with 1,000+ report actions, the useLoadReportActions hook takes over 3000ms to process the data, which causes chat interfaces to freeze and prevents users from efficiently navigating their conversations.

Solution

Optimize useLoadReportActions hook in the following way to reduce its’ processing time:
Replace the current O(n²) Array.map + Array.includes pattern with O(1) Set-based lookups by converting allReportActionIDs into a Set for instant membership testing.
Eliminate redundant iterations by processing all report actions in a single pass, tracking first and last occurrences for both current report and transaction thread simultaneously.

Thread: https://expensify.slack.com/archives/C05LX9D6E07/p1748012519024809

Improvements:
CMD+K showing modal with a 4x CPU throttling.
Before: 4sec
After: 1sec

Upwork Automation - Do Not Edit

• Upwork Job URL: https://www.upwork.com/jobs/~021928073157688472631
• Upwork Job ID: 1928073157688472631
• Last Price Increase: 2025-05-29

Issue Owner

Current Issue Owner: @gedu

[melvin-bot]

Job added to Upwork: https://www.upwork.com/jobs/~021928073157688472631

[melvin-bot]

Triggered auto assignment to Contributor-plus team member for initial proposal review - @fedirjh (External)

[melvin-bot]

Triggered auto assignment to @miljakljajic (Bug), see https://stackoverflow.com/c/expensify/questions/14418 for more details. Please add this bug to a GH project, as outlined in the SO.