diff --git a/changes/bug24769 b/changes/bug24769
new file mode 100644
index 000000000..2893e0ff0
--- /dev/null
+++ b/changes/bug24769
@@ -0,0 +1,7 @@
+  o Minor bugfixes (performance):
+    - Reduce the number of circuits that can be opened at once during the
+      circuit build timeout phase. This is done by increasing the idle timeout
+      to 3 minutes, and lowering the maximum number of concurrent learning
+      circuits to 10. Fixes bug 24769; bugfix on 0.3.1.1-alpha.
+
+
diff --git a/src/or/circuitlist.c b/src/or/circuitlist.c
index db145efc5..29ad9a8ee 100644
--- a/src/or/circuitlist.c
+++ b/src/or/circuitlist.c
@@ -897,8 +897,10 @@ init_circuit_base(circuit_t *circ)
 
 /** If we haven't yet decided on a good timeout value for circuit
  * building, we close idle circuits aggressively so we can get more
- * data points. */
-#define IDLE_TIMEOUT_WHILE_LEARNING (1*60)
+ * data points. These are the default, min, and max consensus values */
+#define DFLT_IDLE_TIMEOUT_WHILE_LEARNING (3*60)
+#define MIN_IDLE_TIMEOUT_WHILE_LEARNING (10)
+#define MAX_IDLE_TIMEOUT_WHILE_LEARNING (1000*60)
 
 /** Allocate space for a new circuit, initializing with <b>p_circ_id</b>
  * and <b>p_conn</b>. Add it to the global circuit list.
@@ -931,7 +933,11 @@ origin_circuit_new(void)
       circuit_build_times_needs_circuits(get_circuit_build_times())) {
     /* Circuits should be shorter lived if we need more of them
      * for learning a good build timeout */
-    circ->circuit_idle_timeout = IDLE_TIMEOUT_WHILE_LEARNING;
+    circ->circuit_idle_timeout =
+      networkstatus_get_param(NULL, "cbtlearntimeout",
+                              DFLT_IDLE_TIMEOUT_WHILE_LEARNING,
+                              MIN_IDLE_TIMEOUT_WHILE_LEARNING,
+                              MAX_IDLE_TIMEOUT_WHILE_LEARNING);
   } else {
     // This should always be larger than the current port prediction time
     // remaining, or else we'll end up with the case where a circuit times out
@@ -951,7 +957,11 @@ origin_circuit_new(void)
                "%d seconds of predictive building remaining.",
                circ->circuit_idle_timeout,
                prediction_time_remaining);
-      circ->circuit_idle_timeout = IDLE_TIMEOUT_WHILE_LEARNING;
+      circ->circuit_idle_timeout =
+          networkstatus_get_param(NULL, "cbtlearntimeout",
+                  DFLT_IDLE_TIMEOUT_WHILE_LEARNING,
+                  MIN_IDLE_TIMEOUT_WHILE_LEARNING,
+                  MAX_IDLE_TIMEOUT_WHILE_LEARNING);
     }
 
     log_info(LD_CIRC,
diff --git a/src/or/circuituse.c b/src/or/circuituse.c
index 1ac950a3c..bc9c4bccb 100644
--- a/src/or/circuituse.c
+++ b/src/or/circuituse.c
@@ -1179,15 +1179,11 @@ needs_hs_client_circuits(time_t now, int *needs_uptime, int *needs_capacity,
           router_have_consensus_path() != CONSENSUS_PATH_UNKNOWN);
 }
 
-/* The minimum number of open slots we should keep in order to preemptively
- * build circuits. */
-#define CBT_MIN_REMAINING_PREEMPTIVE_CIRCUITS 2
-
-/* Check to see if we need more circuits to have a good build timeout. However,
- * leave a couple slots open so that we can still build circuits preemptively
- * as needed. */
-#define CBT_MAX_UNUSED_OPEN_CIRCUITS (MAX_UNUSED_OPEN_CIRCUITS - \
-                                      CBT_MIN_REMAINING_PREEMPTIVE_CIRCUITS)
+/* This is how many circuits can be opened concurrently during the cbt learning
+ * phase. This number cannot exceed the tor-wide MAX_UNUSED_OPEN_CIRCUITS. */
+#define DFLT_CBT_UNUSED_OPEN_CIRCS (10)
+#define MIN_CBT_UNUSED_OPEN_CIRCS 0
+#define MAX_CBT_UNUSED_OPEN_CIRCS MAX_UNUSED_OPEN_CIRCUITS
 
 /* Return true if we need more circuits for a good build timeout.
  * XXXX make the assumption that build timeout streams should be
@@ -1196,7 +1192,10 @@ STATIC int
 needs_circuits_for_build(int num)
 {
   if (router_have_consensus_path() != CONSENSUS_PATH_UNKNOWN) {
-    if (num < CBT_MAX_UNUSED_OPEN_CIRCUITS &&
+    if (num < networkstatus_get_param(NULL, "cbtmaxopencircs",
+                              DFLT_CBT_UNUSED_OPEN_CIRCS,
+                              MIN_CBT_UNUSED_OPEN_CIRCS,
+                              MAX_CBT_UNUSED_OPEN_CIRCS) &&
         !circuit_build_times_disabled(get_options()) &&
         circuit_build_times_needs_circuits_now(get_circuit_build_times())) {
       return 1;