diff --git a/measure-routes.rkt b/measure-routes.rkt
index da53ef9..c6bf6b4 100644
--- a/measure-routes.rkt
+++ b/measure-routes.rkt
@@ -16,6 +16,11 @@
 			   #:column-spec '(number-of-entries
 					   bytes-per-entry
 					   current-memory-use)))
+(define Tprobe (logbook-table E "probe-rate"
+			      #:column-spec '(number-of-entries
+					      positive-probes-per-second
+					      negative-probes-per-second
+					      large-positive-per-second)))
 
 (define *the-routes* #f)
 (define *count* 0)
@@ -32,9 +37,30 @@
   (define perentry (/ delta (exact->inexact n)))
   (write-logbook-datum! T (list n perentry latest-datapoint)))
 
+(define (run-probes!)
+  (define n-probes 100000)
+  (define-syntax-rule (probe message-expr)
+    (let-values (((ignorable-results cpu+gc-time wallclock-time gc-time)
+		  (time-apply
+		   (lambda ()
+		     (let loop ((i 0))
+		       (when (< i n-probes)
+			 (match-value *the-routes* message-expr)
+			 (loop (+ i 1)))))
+		   '())))
+      (/ n-probes (/ wallclock-time 1000.0))))
+  (define positive-probes-per-second (probe (list (random *count*) "hello")))
+  (define large-list (make-list 1000 'x))
+  (define large-positive-per-second (probe (list (random *count*) large-list)))
+  (define negative-probes-per-second (probe (list "hello" (random *count*))))
+  (write-logbook-datum! Tprobe (list *count*
+				     positive-probes-per-second
+				     negative-probes-per-second
+				     large-positive-per-second)))
+
 (record-datapoint!)
 (let loop ((next-count 1000))
-  (when (< next-count 5000000)
+  (when (< next-count 500000)
     (define old-count *count*)
     (define-values (ignorable-results cpu+gc-time wallclock-time gc-time)
       (time-apply
@@ -58,4 +84,5 @@
 				      next-count))
 
     (record-datapoint!)
+    (run-probes!)
     (loop (inexact->exact (truncate (* next-count 1.2))))))