diff --git a/MoltenVK/MoltenVK/API/mvk_private_api.h b/MoltenVK/MoltenVK/API/mvk_private_api.h
index a2183e56..6110ae12 100644
--- a/MoltenVK/MoltenVK/API/mvk_private_api.h
+++ b/MoltenVK/MoltenVK/API/mvk_private_api.h
@@ -408,11 +408,11 @@ typedef struct {
 typedef struct {
 	MVKPerformanceTracker retrieveMTLCommandBuffer;     /** Retrieve a MTLCommandBuffer from a MTLQueue, in milliseconds. */
 	MVKPerformanceTracker commandBufferEncoding;        /** Encode a single VkCommandBuffer to a MTLCommandBuffer (excludes MTLCommandBuffer encoding from configured immediate prefilling), in milliseconds. */
-	MVKPerformanceTracker waitSubmitCommandBuffers;		/** Wait time from initial call to starting the submit and encoding of all VkCommandBuffers in an asynchronous vkQueueSubmit() operation,  in milliseconds. */
+	MVKPerformanceTracker waitSubmitCommandBuffers;		/** Wait time from vkQueueSubmit() call to starting the encoding of the command buffers to the GPU, in milliseconds. Useful when MVK_CONFIG_SYNCHRONOUS_QUEUE_SUBMITS is disabled. */
 	MVKPerformanceTracker submitCommandBuffers;         /** Submit and encode all VkCommandBuffers in a vkQueueSubmit() operation to MTLCommandBuffers (including both prefilled and deferred encoding), in milliseconds. */
 	MVKPerformanceTracker mtlCommandBufferExecution;    /** Execute a MTLCommandBuffer on the GPU, from commit to completion callback, in milliseconds. */
 	MVKPerformanceTracker retrieveCAMetalDrawable;      /** Retrieve next CAMetalDrawable from a CAMetalLayer, in milliseconds. */
-	MVKPerformanceTracker waitPresentSwapchains;		/** Wait time from initial call to starting presentation of the swapchains in an asynchronous vkQueuePresentKHR() operation,  in milliseconds. */
+	MVKPerformanceTracker waitPresentSwapchains;		/** Wait time from vkQueuePresentKHR() call to starting the encoding of the swapchains to the GPU, in milliseconds. Useful when MVK_CONFIG_SYNCHRONOUS_QUEUE_SUBMITS is disabled. */
 	MVKPerformanceTracker presentSwapchains;            /** Present the swapchains in a vkQueuePresentKHR() on the GPU, from commit to presentation callback, in milliseconds. */
 	MVKPerformanceTracker frameInterval;                /** Frame presentation interval (1000/FPS), in milliseconds. */
 } MVKQueuePerformance;
@@ -525,11 +525,12 @@ VKAPI_ATTR VkResult VKAPI_CALL vkGetPhysicalDeviceMetalFeaturesMVK(
  * to tell MoltenVK the limit of the size of your MVKPerformanceStatistics structure. Upon return
  * from this function, the value of *pPerfSize will hold the actual number of bytes copied into
  * your passed MVKPerformanceStatistics structure, which will be the smaller of what your app
- * thinks is the size of MVKPerformanceStatistics, and what MoltenVK thinks it is. This
- * represents the safe access area within the structure for both MoltenVK and your app.
+ * thinks is the size of MVKPerformanceStatistics, and what MoltenVK thinks it is.
  *
  * If the size that MoltenVK expects for MVKPerformanceStatistics is different than the value passed
  * in *pPerfSize, this function will return VK_INCOMPLETE, otherwise it will return VK_SUCCESS.
+ * This indicates that the data returned from this function will likely be incorrect, as the structures
+ * nested under MVKPerformanceStatistics may be different.
  *
  * Although it is not necessary, you can use this function to determine in advance the value
  * that MoltenVK expects the size of MVKPerformanceStatistics to be by setting the value of