Opening a transaction thread can be slow to load sometimes

[rinej]

Details

Problem
Opening transaction threads seems to be much slower than opening a chat or an expense report.

Analysis
After investigating, we noticed that in the transaction opening flow, the formatWithUTCTimeZone function was called multiple times (around 2700 times according to the attached trace). On my smaller testing account, it was called approximately 70 times. The main culprit was the getTransactionDetails function, which was called the same number of times, mostly with the same data.
The most impacted components were MoneyRequestPreviewContent.tsx and MoneyRequestView.tsx.

Solution
By adding memoization, we reduced the rendering amount from around 70 to 26! Additionally, we removed the re-rendering that occurred every time a user hovers over the transaction, providing further benefits. This reduced the call counts by more than 250%.

Testing and Results
I tested this on a smaller account, but the percentage gain on larger accounts should be even more substantial!

Future Optimization Considerations
I considered further optimization by memoizing the getTransactionReportName function, which is also called multiple times. However, since it's not a component, it can only be memoized using utilities like lodash.memoize. In testing, the gain from this was not significant. It might make sense to revisit this when we move to a new memoization library, as mentioned in this Slack thread.

BEFORE:

Before.mp4

AFTER:

After.mp4

Fixed Issues

$ #42687
PROPOSAL: #42687 (comment)

Tests

Offline tests

QA Steps

• Similar as in GH issue -> [pending payment] [$250] [LOW] [Performance] Opening a transaction thread can be slow to load sometimes #42687 (comment)

PR Author Checklist

• I linked the correct issue in the ### Fixed Issues section above
• I wrote clear testing steps that cover the changes made in this PR
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Screenshots/Videos

Android: Native

Android: mWeb Chrome

iOS: Native

iOS: mWeb Safari

MacOS: Chrome / Safari

MacOS: Desktop

[github-actions]

🧪🧪 Use the links below to test this adhoc build on Android, iOS, Desktop, and Web. Happy testing! 🧪🧪

Android 🤖	iOS 🍎
https://ad-hoc-expensify-cash.s3.amazonaws.com/android/43384/index.html	❌ FAILED ❌
	The QR code can't be generated, because the iOS build failed
Desktop 💻	Web 🕸️
https://ad-hoc-expensify-cash.s3.amazonaws.com/desktop/43384/NewExpensify.dmg	https://43384.pr-testing.expensify.com

---

👀 View the workflow run that generated this build 👀

[melvin-bot]

@mountiny Please copy/paste the Reviewer Checklist from here into a new comment on this PR and complete it. If you have the K2 extension, you can simply click: [this button]

[aimane-chnaif]

Reviewer Checklist

• I have verified the author checklist is complete (all boxes are checked off).
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  • I turned off my network connection and tested it while offline to ensure it matches the expected behavior (i.e. verify the default avatar icon is displayed if app is offline)
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  • Android: mWeb Chrome
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• If there are any errors in the console that are unrelated to this PR, I either fixed them (preferred) or linked to where I reported them in Slack
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  • I verified that any callback methods that were added or modified are named for what the method does and never what callback they handle (i.e. toggleReport and not onIconClick).
  • I verified that the left part of a conditional rendering a React component is a boolean and NOT a string, e.g. myBool && <MyComponent />.
  • I verified that comments were added to code that is not self explanatory
  • I verified that any new or modified comments were clear, correct English, and explained "why" the code was doing something instead of only explaining "what" the code was doing.
  • I verified any copy / text shown in the product is localized by adding it to src/languages/* files and using the translation method
  • I verified all numbers, amounts, dates and phone numbers shown in the product are using the localization methods
  • I verified any copy / text that was added to the app is grammatically correct in English. It adheres to proper capitalization guidelines (note: only the first word of header/labels should be capitalized), and is either coming verbatim from figma or has been approved by marketing (in order to get marketing approval, ask the Bug Zero team member to add the Waiting for copy label to the issue)
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• If the PR modifies code that runs when editing or sending messages, I tested and verified there is no unexpected behavior for all supported markdown - URLs, single line code, code blocks, quotes, headings, bold, strikethrough, and italic.
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• If the PR modifies the UI (e.g. new buttons, new UI components, changing the padding/spacing/sizing, moving components, etc) or modifies the form input styles:
  • I verified that all the inputs inside a form are aligned with each other.
  • I added Design label and/or tagged @Expensify/design so the design team can review the changes.
• If a new page is added, I verified it's using the ScrollView component to make it scrollable when more elements are added to the page.
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Screenshots/Videos

Android: Native

Android: mWeb Chrome

iOS: Native

ios.mov

iOS: mWeb Safari

MacOS: Chrome / Safari

web.mov

MacOS: Desktop

[mountiny]

@aimane-chnaif what is your ETA for the testing? thanks!

[aimane-chnaif]

Maybe my account is not heavy enough but transaction detail page loads no more than 1s after api response.
Code looks good and tests well anyway. I am wondering if we should memoize all ReportUtils.getTransactionDetails usages. i.e. DistanceEReceipt, EReceipt

[aimane-chnaif]

Out of scope but app randomly crashed very often while testing:

[rinej]

I am wondering if we should memoize all ReportUtils.getTransactionDetails usages. i.e. DistanceEReceipt, EReceipt

I also considered it, but since it isn't triggered very often and doesn't cause any performance issues (at least from my perspective), I think it's better not to memoize it.

[rinej]

Out of scope but app randomly crashed very often while testing:

Does this happen only on the branch with the PR? I couldn't reproduce it neither on current branch nor on main 🤔

[aimane-chnaif]

Out of scope but app randomly crashed very often while testing:

Does this happen only on the branch with the PR? I couldn't reproduce it neither on current branch nor on main 🤔

NVM. This also happens on main but not constantly reproducible. Maybe related to timezone

[mountiny]

Thanks for testing quick @aimane-chnaif

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✋ This PR was not deployed to staging yet because QA is ongoing. It will be automatically deployed to staging after the next production release.

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platform	result
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🕸 web 🕸	success ✅