Add regression in wall-time that was missed during triage

Author: Mark-Simulacrum

triage/2020-09-15.md

@@ -5,11 +5,12 @@ See the [README](README.md) for details on how this log was gathered.
 Triage done by @Mark-Simulacrum.
 Revision range: [35fc8359868e65a0970094f648ba87fce634e8c7..a53f449516f23486d2dfd4e5685d4e869e8591d9](https://perf.rust-lang.org/index.html?start=35fc8359868e65a0970094f648ba87fce634e8c7&end=a53f449516f23486d2dfd4e5685d4e869e8591d9&absolute=false&stat=instructions%3Au)
 
-0 Regressions, 2 Improvements, 0 of them in rollups.
+1 Regressions, 2 Improvements, 0 of them in rollups.
 
 #### Regressions
 
-No regressions noted.
+[Removing the `def_id` field from hot `ParamEnv` to make it smaller #76244](https://github.com/rust-lang/rust/pull/76244)
+- A 3% instruction and [25% wall-time](https://perf.rust-lang.org/compare.html?start=a055c5a1bd95e029e9b31891db63b6dc8258b472&end=7402a394471a6738a40fea7d4f1891666e5a80c5&stat=task-clock) regression on some benchmarks.
 
 #### Improvements
 
@@ -21,4 +22,5 @@ No regressions noted.
 
 #### Nags requiring follow up
 
-None
+* [#76244](https://github.com/rust-lang/rust/pull/76244#issuecomment-694459840)
+    * Consider a revert if no comments