Revert: Performance: Parallelize recursive directory copying (#2409)

[ivan-ottinger]

Summary

• Reverts the changes from PR Performance: Parallelize recursive directory copying #2409
• Brings back the sequential recursiveCopyDirectory implementation
• Removes direct usage of fs-extra's copy in favor of the custom implementation

The copy logic will be revisited in #2502.

Related issues

• Reverts Performance: Parallelize recursive directory copying #2409

Testing Instructions

1. Check out the PR branch and build the app with npm install && npm start.
2. Create several new sites.
3. The process should work correctly, the sites should get created and run without any issues.

[wpmobilebot]

📊 Performance Test Results

Comparing da1097b vs trunk

site-editor

Metric	trunk	da1097b	Diff	Change
load	2867.00 ms	2923.00 ms	+56.00 ms	🔴 2.0%

site-startup

Metric	trunk	da1097b	Diff	Change
siteCreation	7067.00 ms	7075.00 ms	+8.00 ms	🔴 0.1%
siteStartup	3925.00 ms	3934.00 ms	+9.00 ms	🔴 0.2%

---

Results are median values from multiple test runs.

Legend: 🟢 Improvement (faster) | 🔴 Regression (slower) | ⚪ No change

[sejas]

The revert works as expected. I was able to create and start new sites.

[epeicher]

Thanks @ivan-ottinger for working on a better option! I have tested creating multiple sites on both Mac and Windows, and I have not found any issues. On Windows, the performance of creating a site is still not good, but I have compared with trunk and this branch seems to be slightly better.LGTM!

Sites created on Mac	Sites created onWindows

[ivan-ottinger]

Thank you for your reviews, everyone!

For completeness, the performance results of the original PR showed site creation slowdown despite my results in manual testing. This was a motivation to revert those changes in this PR.

Interestingly, the performance results on this PR does not show any significant difference. The same is true when running the performance tests locally:

  ┌────────────────────────┬───────────────┐
  │         Branch         │ Site Creation │
  ├────────────────────────┼───────────────┤
  │ revert/file-copy-logic │ 7096 ms       │
  ├────────────────────────┼───────────────┤
  │ trunk                  │ 7039 ms       │
  └────────────────────────┴───────────────┘

Regardless, I will merge this PR to unblock Studio release and then continue working on #2502 which could speed site creation up.