Control Flow Analysis Performance Regression #62050

🔎 Search Terms

Control Flow

🕗 Version & Regression Information

• This changed in commit or PR ： Omit effects-free conditional constructs from control flow graph #58013

⏯ Playground Link

No response

💻 Code

🙁 Actual behavior

I encountered a severe performance regression when type-checking a very large JavaScript file (~360,000 lines).

v4.9.5: Type-checking takes ~16,476ms.

v5.5.4: Type-checking time increases to ~64,196ms (4x slower).

Steps to Reproduce:

1. Clone the attached project and run:

npm install
node checker.js

2. Switch TypeScript versions (e.g., between v4.9.5 and v5.5.4) and re-test.

After testing, I believe this regression was introduced by PR #58013. When I revert this commit, the performance returns to v4.9.5 levels.

testLargeFile.zip

🙂 Expected behavior

The performance is the same as v4.9.5

Additional information about the issue

No response