diff --git a/racket/src/racket/include/schthread.h b/racket/src/racket/include/schthread.h
index 4aa32c77ac..cd9dc4fa44 100644
--- a/racket/src/racket/include/schthread.h
+++ b/racket/src/racket/include/schthread.h
@@ -237,6 +237,7 @@ typedef struct Thread_Local_Variables {
   struct Scheme_Thread *gc_prep_thread_chain_;
   struct Scheme_Thread_Set *scheme_thread_set_top_;
   struct Scheme_Current_LWC *scheme_current_lwc_;
+  intptr_t process_time_at_swap_;
   int num_running_threads_;
   int swap_no_setjmp_;
   int thread_swap_count_;
@@ -624,6 +625,7 @@ XFORM_GC_VARIABLE_STACK_THROUGH_THREAD_LOCAL;
 #define num_running_threads XOA (scheme_get_thread_local_variables()->num_running_threads_)
 #define swap_no_setjmp XOA (scheme_get_thread_local_variables()->swap_no_setjmp_)
 #define thread_swap_count XOA (scheme_get_thread_local_variables()->thread_swap_count_)
+#define process_time_at_swap XOA (scheme_get_thread_local_variables()->process_time_at_swap_)
 #define scheme_did_gc_count XOA (scheme_get_thread_local_variables()->scheme_did_gc_count_)
 #define scheme_future_state XOA (scheme_get_thread_local_variables()->scheme_future_state_)
 #define scheme_future_thread_state XOA (scheme_get_thread_local_variables()->scheme_future_thread_state_)
diff --git a/racket/src/racket/src/thread.c b/racket/src/racket/src/thread.c
index 6af5b83df1..fbd201289e 100644
--- a/racket/src/racket/src/thread.c
+++ b/racket/src/racket/src/thread.c
@@ -175,6 +175,7 @@ THREAD_LOCAL_DECL(static int swap_no_setjmp = 0);
 
 THREAD_LOCAL_DECL(static int thread_swap_count);
 THREAD_LOCAL_DECL(int scheme_did_gc_count);
+THREAD_LOCAL_DECL(static intptr_t process_time_at_swap);
 
 SHARED_OK static int init_load_on_demand = 1;
 
@@ -2720,11 +2721,7 @@ static void do_swap_thread()
       scheme_takeover_stacks(scheme_current_thread);
     }
 
-    {
-      intptr_t cpm;
-      cpm = scheme_get_process_milliseconds();
-      scheme_current_thread->current_start_process_msec = cpm;
-    }
+    scheme_current_thread->current_start_process_msec = process_time_at_swap;
 
     if (scheme_current_thread->return_marks_to) {
       stash_current_marks();
@@ -2737,6 +2734,7 @@ static void do_swap_thread()
       intptr_t cpm;
       cpm = scheme_get_process_milliseconds();
       scheme_current_thread->accum_process_msec += (cpm - scheme_current_thread->current_start_process_msec);
+      process_time_at_swap = cpm;
     }
 
     swap_target = NULL;
@@ -3059,11 +3057,7 @@ static void start_child(Scheme_Thread * volatile child,
       }
     }
 
-    {
-      intptr_t cpm;
-      cpm = scheme_get_process_milliseconds();
-      scheme_current_thread->current_start_process_msec = cpm;
-    }
+    scheme_current_thread->current_start_process_msec = process_time_at_swap;
 
     RESETJMP(child);