Index: b/agent/call-scd.c
===================================================================
--- b/agent/call-scd.c
+++ b/agent/call-scd.c
@@ -407,7 +407,9 @@
 
   primary_scd_ctx = ctx;
   primary_scd_ctx_reusable = 0;
-
+  /* notify the main loop that something has changed */
+  interrupt_main_thread_loop ();
+  
  leave:
   xfree (abs_homedir);
   if (err)
Index: b/agent/gpg-agent.c
===================================================================
--- b/agent/gpg-agent.c
+++ b/agent/gpg-agent.c
@@ -2249,6 +2249,26 @@
 }
 
 
+static int
+need_tick (void)
+{
+#ifdef HAVE_W32_SYSTEM
+  /* We do not know how to interrupt the select loop on Windows, so we
+     always need a short tick there. */
+  return 1;
+#else
+  /* if we were invoked like "gpg-agent cmd arg1 arg2" then we need to
+     watch our parent. */
+  if (parent_pid != (pid_t)(-1))
+    return 1;
+  /* if scdaemon is running, we need to check that it's alive */
+  if (agent_scd_check_running ())
+    return 1;
+  /* otherwise, nothing fine-grained to do. */
+  return 0;
+#endif /*HAVE_W32_SYSTEM*/
+}
+
 
 /* This is the worker for the ticker.  It is called every few seconds
    and may only do fast operations. */
@@ -2307,7 +2327,7 @@
 
 #ifndef HAVE_W32_SYSTEM
 /* The signal handler for this program.  It is expected to be run in
-   its own trhead and not in the context of a signal handler.  */
+   its own thread and not in the context of a signal handler.  */
 static void
 handle_signal (int signo)
 {
@@ -2843,6 +2863,9 @@
          thus a simple assignment is fine to copy the entire set.  */
       read_fdset = fdset;
 
+      /* avoid a fine-grained timer if we don't need one: */
+      timertbl[0].interval.tv_sec = need_tick () ? TIMERTICK_INTERVAL : 0;
+
       /* loop through all timers, fire any registered functions, and
          plan next timer to trigger */
       npth_clock_gettime (&curtime);