UX: Faster perceived performance of popup

[darkwing]

Description

With #20843 we made JavaScript for the extension load asynchronously, which helped to get the popup displaying faster. Unfortunately with a timeout of 0 to kick off the process, the popup still acts as though it's blocking (not async). By adding a small timeout, the popup display much faster.

Manual testing steps

1. On current develop, mentally note how much time it takes for the popup to display
2. Check out this PR
3. Restart the extension
4. See that the popup displays much faster!

Pre-merge author checklist

• I’ve followed MetaMask Coding Standards.
• I've clearly explained:
  • What problem this PR is solving.
  • How this problem was solved.
  • How reviewers can test my changes.
• I’ve indicated what issue this PR is linked to: Fixes #???
• I’ve included tests if applicable.
• I’ve documented any added code.
• I’ve applied the right labels on the PR (see labeling guidelines).
• I’ve properly set the pull request status:
  • In case it's not yet "ready for review", I've set it to "draft".
  • In case it's "ready for review", I've changed it from "draft" to "non-draft".

Pre-merge reviewer checklist

• I've manually tested the PR (e.g. pull and build branch, run the app, test code being changed).
• I confirm that this PR addresses all acceptance criteria described in the ticket it closes and includes the necessary testing evidence such as recordings and or screenshots.

[github-actions]

CLA Signature Action: All authors have signed the CLA. You may need to manually re-run the blocking PR check if it doesn't pass in a few minutes.

[metamaskbot]

Builds ready [30b77da]

• builds: chrome, firefox
• builds (beta): chrome
• builds (flask): chrome, firefox
• builds (MMI): chrome, firefox
• build viz: Build System
• mv3: Background Module Init Stats
• mv3: UI Init Stats
• mv3: Module Load Stats
• mv3: Bundle Size Stats
• mv2: E2e Actions Stats
• code coverage: Report
• storybook: Storybook
• typescript migration: Dashboard
• all artifacts
• bundle viz:

  • background: 0, 1, 2, 3, 4
  • common: 0, 1, 2, 3, 4, 5, 6, 7
  • content-script: 0
  • contentscript: contentscript
  • disable-console: disable-console
  • inpage: inpage
  • policy-load: policy-load
  • sentry-install: sentry-install
  • ui: 0, 1, 10, 11, 12, 2, 3, 4, 5, 6, 7, 8, 9

Page Load Metrics (696 ± 324 ms)

Platform	Page	Metric	Min (ms)	Max (ms)	Average (ms)	StandardDeviation (ms)	MarginOfError (ms)
Chrome	Home	firstPaint	80	123	96	12	6
		domContentLoaded	63	113	87	17	8
		load	74	1562	696	675	324
		domInteractive	63	113	87	17	8

Bundle size diffs

• background: 0 Bytes (0.00%)
• ui: 0 Bytes (0.00%)
• common: 0 Bytes (0.00%)

[codecov]

Codecov Report

Patch and project coverage have no change.

Comparison is base (315c043) 68.34% compared to head (30b77da) 68.34%.

Additional details and impacted files

@@           Coverage Diff            @@
##           develop   #21015   +/-   ##
========================================
  Coverage    68.34%   68.34%           
========================================
  Files         1007     1007           
  Lines        40254    40254           
  Branches     10761    10761           
========================================
  Hits         27508    27508           
  Misses       12746    12746           

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