diff --git a/docs/dev/ENVIRONMENT.md b/docs/dev/ENVIRONMENT.md
index 27bf42846e..70584350e4 100644
--- a/docs/dev/ENVIRONMENT.md
+++ b/docs/dev/ENVIRONMENT.md
@@ -65,6 +65,8 @@ The code reads environment names through `getenv`, `IsEnvironmentSet`, `kibSetti
 | Name | Kind | Source | Default | Description |
 |------|------|--------|---------|-------------|
 | `ANYPS5_GPU` | string | `core/libs/prx/libSceAgcDriver/Execution/src/VulkanDevice.cpp` |  | restricts physical device selection to device names containing this case-insensitive substring |
+| `ANYPS5_OVERLAY` | string | `core/libs/prx/libSceAgcDriver/Execution/src/PerformanceOverlay.cpp` | 0 | 1 shows the performance overlay; 0 or unset hides it, and any other value is refused |
+| `ANYPS5_OVERLAY_POS` | string | `core/libs/prx/libSceAgcDriver/Execution/src/PerformanceOverlay.cpp` | tl | the overlay's corner: tl, tr, bl or br |
 | `ANYPS5_PRESENT_MODE` | string | `core/libs/prx/libSceAgcDriver/Execution/src/VulkanDevice.cpp` | fifo | selects the swapchain present mode: fifo, fifo_latest_ready, mailbox or immediate |
 | `ANYPS5_REQUIRE_DESCRIPTOR_BINDING_FLAGS` | presence | `core/libs/prx/libSceAgcDriver/tests/ComputePipelineReplay.cpp` |  | fails the replay test instead of accepting a device that refuses descriptor binding flags |
 | `ANYPS5_REQUIRE_ROBUST2` | presence | `core/libs/prx/libSceAgcDriver/tests/execution/LdsMixedWidthAtomics.cpp` |  | fails the LDS lock-budget test when the device does not enable robustBufferAccess2, instead of only printing it |