diff --git a/common/threads.c b/common/threads.c
index 00420d9c..6a901e8d 100644
--- a/common/threads.c
+++ b/common/threads.c
@@ -82,6 +82,12 @@ InterruptThreadProgress__(void)
 int numthreads = 1;
 CRITICAL_SECTION crit;
 
+void
+LowerProcessPriority(void)
+{
+    SetPriorityClass(GetCurrentProcess(), BELOW_NORMAL_PRIORITY_CLASS);
+}
+
 int
 GetDefaultThreads(void)
 {
@@ -170,6 +176,12 @@ RunThreadsOn(int start, int workcnt, void *(func)(void *), void *arg)
 int numthreads = 1;
 pthread_mutex_t *my_mutex;
 
+void
+LowerProcessPriority(void)
+{
+    /* not implemented for now */
+}
+
 int
 GetDefaultThreads(void)
 {
diff --git a/include/common/threads.h b/include/common/threads.h
index ef1c7242..b0b37908 100644
--- a/include/common/threads.h
+++ b/include/common/threads.h
@@ -5,6 +5,7 @@
 
 extern int numthreads;
 
+void LowerProcessPriority(void);
 int GetDefaultThreads(void);
 int GetMaxThreads(void); /* returns 0 if no limit specified */
 int GetThreadWork(void);
diff --git a/light/light.c b/light/light.c
index 47ac8858..d1e17efa 100644
--- a/light/light.c
+++ b/light/light.c
@@ -270,6 +270,7 @@ main(int argc, const char **argv)
     init_log("light.log");
     logprint("---- light / TyrUtils " stringify(TYRUTILS_VERSION) " ----\n");
 
+    LowerProcessPriority();
     numthreads = GetDefaultThreads();
 
     for (i = 1; i < argc; i++) {
diff --git a/vis/vis.c b/vis/vis.c
index db96264f..3a0a0dbe 100644
--- a/vis/vis.c
+++ b/vis/vis.c
@@ -1182,6 +1182,7 @@ main(int argc, char **argv)
     init_log("vis.log");
     logprint("---- vis / TyrUtils " stringify(TYRUTILS_VERSION) " ----\n");
 
+    LowerProcessPriority();
     numthreads = GetDefaultThreads();
 
     for (i = 1; i < argc; i++) {