diff --git a/CMakeLists.txt b/CMakeLists.txt
index f79dc5d43..e5f141f74 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -155,7 +155,7 @@ endif()
 # Generic build options
 set(DEFAULT_MALLOC "system")
 if("${CMAKE_SYSTEM_NAME}" STREQUAL "Linux")
-  set(DEFAULT_MALLOC "tcmalloc")
+  set(DEFAULT_MALLOC "mimalloc")
 endif()
 
 if("${CMAKE_SYSTEM_NAME}" STREQUAL "Linux")
@@ -179,7 +179,7 @@ endif()
 pika_option(
   PIKA_WITH_MALLOC
   STRING
-  "Define which allocator should be linked in. Options are: system, tcmalloc, jemalloc, mimalloc, tbbmalloc, and custom (default: tcmalloc)"
+  "Define which allocator should be linked in. Options are: system, tcmalloc, jemalloc, mimalloc, tbbmalloc, and custom (default: ${DEFAULT_MALLOC})"
   ${DEFAULT_MALLOC}
   STRINGS "system;tcmalloc;jemalloc;mimalloc;tbbmalloc;custom"
 )
diff --git a/cmake/pika_setup_allocator.cmake b/cmake/pika_setup_allocator.cmake
index 5e358edc4..f7adb3b51 100644
--- a/cmake/pika_setup_allocator.cmake
+++ b/cmake/pika_setup_allocator.cmake
@@ -90,6 +90,10 @@ if(NOT TARGET pika_dependencies_allocator)
         )
       endif()
       set(_use_custom_allocator TRUE)
+
+      pika_warn(
+        "pika is using mimalloc as the allocator. Typically, exporting the following environment variables will further improve performance: MIMALLOC_EAGER_COMMIT_DELAY=0 and MIMALLOC_LARGE_OS_PAGES=1."
+      )
     endif()
 
     # ##########################################################################