tracing: skipping scope-manager's populateGlobalsFromLib

Author: JoshuaKGoldberg

README.md

@@ -64,10 +64,38 @@ The `traces/` directory contains more specific traces for investigations.
 
 > ✨ You might consider using [0x](https://github.com/davidmarkclements/0x) for nice flamegraph visuals.
 
+All comparisons were run on a common shape of linting: 1024 files with the "even" (triangle-shaped) imports layout.
+
+### Comparison: Globals in Scopes
+
+> 📌 Filed on typescript-eslint as [⚡ Performance: Overhead of populateGlobalsFromLib in scope-manager](https://github.com/typescript-eslint/typescript-eslint/issues/9575).
+
+This trace shows the impact of `@typescript-eslint/scope-manager`'s `populateGlobalsFromLib`.
+
+See `traces/globals-scope-manager/`:
+
+- `baseline.cpuprofile`: Baseline measurement with no changes
+- `skipping.cpuprofile`: Commenting out the contents of `populateGlobalsFromLib`
+
+They were generated with:
+
+```shell
+cd files-1024-layout-even-singlerun-true-types-service
+node --cpu-prof --cpu-prof-interval=100 --cpu-prof-name=baseline.cpuprofile ../../node_modules/eslint/bin/eslint.js
+# clear ../../node_modules/@typescript-eslint/scope-manager/dist/referencer/Referencer.js > populateGlobalsFromLib
+node --cpu-prof --cpu-prof-interval=100 --cpu-prof-name=skipping.cpuprofile ../../node_modules/eslint/bin/eslint.js
+```
+
+Hyperfine measurements show a ~20% improvement in lint time:
+
+| Variant  | Measurement       | User Time |
+| -------- | ----------------- | --------- |
+| Baseline | 3.137 s ± 0.024 s | 4.417 s   |
+| Skipping | 2.477 s ± 0.014 s | 3.501 s   |
+
 ### Comparison: Project and Project Service
 
-This is a preliminary trace to start debugging.
-It was run a common shape of linting: 1024 files with the "even" (triangle-shaped) imports layout.
+This is a preliminary trace to start debugging their differences.
 
 See `traces/Project 1 - Service 2.cpuprofile`.
 
@@ -95,7 +123,6 @@ Comparing equivalent code paths:
 > 📌 Filed on TypeScript as [⚡ Performance: Project service spends excess time cleaning client files when called synchronously](https://github.com/microsoft/TypeScript/issues/59335).
 
 This comparison shows the cost of the TypeScript project service calling `cleanupProjectsAndScriptInfos`.
-It also was run on a common shape of linting: 1024 files with the "even" (triangle-shaped) imports layout.
 
 See `traces/service-file-cleanup/`:
 
@@ -123,7 +150,6 @@ Hyperfine measurements show a ~15-20% improvement in lint time:
 > 📌 Filed on TypeScript as [⚡ Performance: Project service doesn't cache all fs.statSync](https://github.com/microsoft/TypeScript/issues/59338).
 
 This comparison shows the cost uncached `fs.statSync` calls inside the project service.
-It also was run on a common shape of linting: 1024 files with the "even" (triangle-shaped) imports layout.
 
 See `traces/service-uncached-stats/`:
 
@@ -180,7 +206,6 @@ Hyperfine measurements show a ~7-12% improvement in lint time:
 > 📌 Filed on TypeScript as [⚡ Performance: Project service doesn't cache all fs.realpath](https://github.com/microsoft/TypeScript/issues/59342).
 
 This comparison shows the cost uncached `fs.realpath` calls inside the project service.
-It also was run on a common shape of linting: 1024 files with the "even" (triangle-shaped) imports layout.
 
 See `traces/service-uncached-realpaths/`: