diff --git a/bin/ikarus b/bin/ikarus
index 4191d2d..b9066db 100755
Binary files a/bin/ikarus and b/bin/ikarus differ
diff --git a/bin/ikarus-runtime.c b/bin/ikarus-runtime.c
index 1938d61..365240e 100644
--- a/bin/ikarus-runtime.c
+++ b/bin/ikarus-runtime.c
@@ -11,6 +11,8 @@
 #include <unistd.h>
 #include <sys/mman.h>
 #include <assert.h>
+#include <sys/time.h>
+#include <sys/resource.h>
 
 #include <uuid/uuid.h>
 
@@ -858,3 +860,23 @@ ikrt_register_guardian(ikp tc, ikp obj, ikpcb* pcb){
   g->count++;
   return 0;
 }
+
+
+ikp 
+ikrt_stats_now(ikp t, ikpcb* pcb){
+  struct rusage r;
+  struct timeval s;
+
+  gettimeofday(&s, 0);
+  getrusage(RUSAGE_SELF, &r);
+  ref(t, off_record_data)                = fix(r.ru_utime.tv_sec);
+  ref(t, off_record_data + wordsize)     = fix(r.ru_utime.tv_usec);
+  ref(t, off_record_data + 2 * wordsize) = fix(r.ru_stime.tv_sec);
+  ref(t, off_record_data + 3 * wordsize) = fix(r.ru_stime.tv_usec);
+  ref(t, off_record_data + 4 * wordsize) = fix(s.tv_sec);
+  ref(t, off_record_data + 5 * wordsize) = fix(s.tv_usec);
+  return void_object;
+}
+
+
+
diff --git a/lab/sudoku.txt b/lab/sudoku.txt
index fc2007c..03be64f 100644
--- a/lab/sudoku.txt
+++ b/lab/sudoku.txt
@@ -498,3 +498,1143 @@
  "009040301"
  "000702000"
  "000008006")
+("grid"
+ "400000805"
+ "030000000"
+ "000700000"
+ "020000060"
+ "000080400"
+ "000010000"
+ "000603070"
+ "500200000"
+ "104000000")
+
+
+("grid"
+ "520006000"
+ "000000701"
+ "300000000"
+ "000400800"
+ "600000050"
+ "000000000"
+ "041800000"
+ "000030020"
+ "008700000")
+
+
+("grid"
+ "600000803"
+ "040700000"
+ "000000000"
+ "000504070"
+ "300200000"
+ "106000000"
+ "020000050"
+ "000080600"
+ "000010000")
+
+
+("grid"
+ "480300000"
+ "000000071"
+ "020000000"
+ "705000060"
+ "000200800"
+ "000000000"
+ "001076000"
+ "300000400"
+ "000050000")
+
+
+("grid"
+ "000014000"
+ "030000200"
+ "070000000"
+ "000900030"
+ "601000000"
+ "000000080"
+ "200000104"
+ "000050600"
+ "000708000")
+
+
+("grid"
+ "000000520"
+ "080400000"
+ "030009000"
+ "501000600"
+ "200700000"
+ "000300000"
+ "600010000"
+ "000000704"
+ "000000030")
+
+
+("grid"
+ "602050000"
+ "000003040"
+ "000000000"
+ "430008000"
+ "010000200"
+ "000000700"
+ "500270000"
+ "000000081"
+ "000600000")
+
+
+("grid"
+ "052400000"
+ "000070100"
+ "000000000"
+ "000802000"
+ "300000600"
+ "090500000"
+ "106030000"
+ "000000089"
+ "700000000")
+
+
+("grid"
+ "602050000"
+ "000004030"
+ "000000000"
+ "430008000"
+ "010000200"
+ "000000700"
+ "500270000"
+ "000000081"
+ "000600000")
+
+
+("grid"
+ "092300000"
+ "000080100"
+ "000000000"
+ "107040000"
+ "000000065"
+ "800000000"
+ "060502000"
+ "400000700"
+ "000900000")
+
+
+("grid"
+ "600302000"
+ "050000010"
+ "000000000"
+ "702600000"
+ "000000054"
+ "300000000"
+ "080150000"
+ "000040200"
+ "000000700")
+
+
+("grid"
+ "060501090"
+ "100090053"
+ "900007000"
+ "040800070"
+ "000000508"
+ "081705030"
+ "000050200"
+ "000000000"
+ "076008000")
+
+
+("grid"
+ "005000987"
+ "040050001"
+ "007000000"
+ "200048000"
+ "090100000"
+ "600200000"
+ "300600200"
+ "000009070"
+ "000000500")
+
+
+("grid"
+ "306070000"
+ "000000051"
+ "800000000"
+ "010405000"
+ "700000600"
+ "000200000"
+ "020000040"
+ "000080300"
+ "000500000")
+
+
+("grid"
+ "100000308"
+ "070400000"
+ "000000000"
+ "203010000"
+ "000000095"
+ "800000000"
+ "050600070"
+ "000080200"
+ "040000000")
+
+
+("grid"
+ "600302000"
+ "040000010"
+ "000000000"
+ "702600000"
+ "000000054"
+ "300000000"
+ "080150000"
+ "000040200"
+ "000000700")
+
+
+("grid"
+ "000030090"
+ "000200001"
+ "050900000"
+ "000000000"
+ "102080406"
+ "080500020"
+ "075000000"
+ "401006003"
+ "000004060")
+
+
+("grid"
+ "450000030"
+ "000801000"
+ "090000000"
+ "000050090"
+ "200700000"
+ "800000000"
+ "010040000"
+ "000000702"
+ "000600800")
+
+
+("grid"
+ "023700006"
+ "800060590"
+ "900000700"
+ "000040970"
+ "307096002"
+ "000000000"
+ "500470000"
+ "000002000"
+ "080000000")
+
+
+("grid"
+ "008400030"
+ "000300000"
+ "900001574"
+ "790008000"
+ "000007005"
+ "140000020"
+ "009060002"
+ "050000400"
+ "000090056")
+
+
+("grid"
+ "098010000"
+ "200000060"
+ "000000000"
+ "000302050"
+ "084000000"
+ "000600000"
+ "000040809"
+ "300500000"
+ "000000100")
+
+
+("grid"
+ "002470058"
+ "000000000"
+ "000001040"
+ "000020009"
+ "528090400"
+ "009000100"
+ "000000030"
+ "300007500"
+ "685002000")
+
+
+("grid"
+ "400000805"
+ "030000000"
+ "000700000"
+ "020000060"
+ "000050400"
+ "000010000"
+ "000603070"
+ "500200000"
+ "109000000")
+
+
+("grid"
+ "020300000"
+ "063000005"
+ "800000001"
+ "500009030"
+ "000700000"
+ "000100008"
+ "087900260"
+ "000006070"
+ "006007004")
+
+
+("grid"
+ "100000709"
+ "040007200"
+ "800000000"
+ "070010060"
+ "300000005"
+ "060040020"
+ "000000008"
+ "005300070"
+ "702000046")
+
+
+("grid"
+ "400000300"
+ "000802000"
+ "000700000"
+ "000100087"
+ "340000000"
+ "600000000"
+ "500060000"
+ "000010400"
+ "082000000")
+
+
+("grid"
+ "000000071"
+ "020800000"
+ "000403000"
+ "700060050"
+ "000200300"
+ "900000000"
+ "600070000"
+ "080000400"
+ "000050000")
+
+
+("grid"
+ "600302000"
+ "040000080"
+ "000000000"
+ "702600000"
+ "000000054"
+ "300000000"
+ "080150000"
+ "000080200"
+ "000000700")
+
+
+("grid"
+ "047080001"
+ "000000000"
+ "000600700"
+ "600003570"
+ "000005000"
+ "010060000"
+ "280040000"
+ "090100040"
+ "000020690")
+
+
+("grid"
+ "000000801"
+ "700200000"
+ "000506000"
+ "000700050"
+ "010000300"
+ "080000000"
+ "500000020"
+ "040080000"
+ "600030000")
+
+
+("grid"
+ "380600000"
+ "009000000"
+ "020030510"
+ "000005000"
+ "030010060"
+ "000400000"
+ "017050080"
+ "000000900"
+ "000007032")
+
+
+("grid"
+ "000500000"
+ "000000506"
+ "970000020"
+ "004802000"
+ "250100030"
+ "080030000"
+ "000004070"
+ "013050090"
+ "020003100")
+
+
+("grid"
+ "020000000"
+ "305062009"
+ "068000300"
+ "050000000"
+ "000640802"
+ "004700900"
+ "003000001"
+ "000006000"
+ "170430000")
+
+
+("grid"
+ "080040000"
+ "300000010"
+ "000000020"
+ "005000406"
+ "900100800"
+ "200000000"
+ "000309000"
+ "060000500"
+ "000200000")
+
+
+("grid"
+ "008090100"
+ "060500020"
+ "000006000"
+ "030107050"
+ "000000009"
+ "004000300"
+ "050000200"
+ "070003080"
+ "200700004")
+
+
+("grid"
+ "400000508"
+ "030000000"
+ "000700000"
+ "020000060"
+ "000050800"
+ "000010000"
+ "000603070"
+ "500200000"
+ "108000000")
+
+
+("grid"
+ "100000308"
+ "060400000"
+ "000000000"
+ "203010000"
+ "000000095"
+ "800000000"
+ "050600070"
+ "000080200"
+ "040000000")
+
+
+("grid"
+ "100006080"
+ "064000000"
+ "000040007"
+ "000090600"
+ "070400500"
+ "500070100"
+ "050000320"
+ "300008000"
+ "400000000")
+
+
+("grid"
+ "249060003"
+ "030000200"
+ "800000005"
+ "000006000"
+ "000200000"
+ "010040820"
+ "090500700"
+ "004000001"
+ "070003000")
+
+
+("grid"
+ "000800009"
+ "087300040"
+ "600700000"
+ "008500970"
+ "000000000"
+ "043007500"
+ "000003000"
+ "030001450"
+ "400002001")
+
+
+("grid"
+ "000501000"
+ "090000800"
+ "060000000"
+ "401000000"
+ "000070090"
+ "000000030"
+ "800000105"
+ "000200400"
+ "000360000")
+
+
+("grid"
+ "000000801"
+ "600200000"
+ "000705000"
+ "000600020"
+ "010000300"
+ "080000000"
+ "200000070"
+ "030080000"
+ "500040000")
+
+
+("grid"
+ "047600050"
+ "803000002"
+ "000009000"
+ "000805006"
+ "000100000"
+ "602400000"
+ "078000510"
+ "006000040"
+ "090004007")
+
+
+("grid"
+ "000007095"
+ "000001000"
+ "860020000"
+ "020073008"
+ "500000060"
+ "003004900"
+ "305000417"
+ "240000000"
+ "000000000")
+
+
+("grid"
+ "040500000"
+ "800090030"
+ "076020000"
+ "014600000"
+ "000009007"
+ "000003600"
+ "001004050"
+ "060000003"
+ "007100200")
+
+
+("grid"
+ "083400000"
+ "000070050"
+ "000000000"
+ "040108000"
+ "000000027"
+ "000300000"
+ "206050000"
+ "500000800"
+ "000000100")
+
+
+("grid"
+ "009000003"
+ "000009000"
+ "700000506"
+ "006500400"
+ "000300000"
+ "028000000"
+ "300750600"
+ "600000000"
+ "000120308")
+
+
+("grid"
+ "026039000"
+ "000600001"
+ "900000700"
+ "000004009"
+ "050000200"
+ "008500000"
+ "300200900"
+ "400007620"
+ "000000004")
+
+
+("grid"
+ "203080000"
+ "800700000"
+ "000000100"
+ "060507000"
+ "400000030"
+ "000100000"
+ "000000082"
+ "050000600"
+ "010000000")
+
+
+("grid"
+ "600302000"
+ "010000050"
+ "000000000"
+ "702600000"
+ "000000084"
+ "300000000"
+ "080150000"
+ "000080200"
+ "000000700")
+
+
+("grid"
+ "100000900"
+ "064001070"
+ "070040000"
+ "000300000"
+ "308900500"
+ "007000020"
+ "000060709"
+ "000004010"
+ "000129030")
+
+
+("grid"
+ "000000000"
+ "900000084"
+ "062300050"
+ "000600045"
+ "300010006"
+ "000900070"
+ "000100000"
+ "405002000"
+ "030800009")
+
+
+("grid"
+ "020000593"
+ "800500460"
+ "940060008"
+ "002030000"
+ "060080730"
+ "700200000"
+ "000040380"
+ "070000600"
+ "000000005")
+
+
+("grid"
+ "904005000"
+ "250600100"
+ "310000008"
+ "070009000"
+ "400260000"
+ "001470000"
+ "700000002"
+ "000300806"
+ "040000090")
+
+
+("grid"
+ "000520000"
+ "090003004"
+ "000000700"
+ "010000040"
+ "080045300"
+ "600010008"
+ "702000000"
+ "008000032"
+ "040080010")
+
+
+("grid"
+ "530020900"
+ "024030050"
+ "009000000"
+ "000010827"
+ "000700000"
+ "000098100"
+ "000000000"
+ "006400009"
+ "102050430")
+
+
+("grid"
+ "100007860"
+ "007008010"
+ "800200009"
+ "000000002"
+ "400010000"
+ "009005000"
+ "608000000"
+ "000050900"
+ "000009304")
+
+
+("grid"
+ "000050001"
+ "100000070"
+ "060000080"
+ "000004000"
+ "009010300"
+ "000596020"
+ "080062007"
+ "007000000"
+ "305070200")
+
+
+("grid"
+ "047020000"
+ "800001000"
+ "030000902"
+ "000005000"
+ "600810050"
+ "000040000"
+ "070000304"
+ "000900010"
+ "400270800")
+
+
+("grid"
+ "000000940"
+ "000090005"
+ "300005070"
+ "080400100"
+ "463000000"
+ "000007080"
+ "800700000"
+ "700000028"
+ "050260000")
+
+
+("grid"
+ "020000006"
+ "000041000"
+ "007800001"
+ "000000700"
+ "003700000"
+ "600412000"
+ "010074005"
+ "008050070"
+ "000003900")
+
+
+("grid"
+ "100000308"
+ "060400000"
+ "000000000"
+ "203010000"
+ "000000075"
+ "800000000"
+ "070500060"
+ "000080200"
+ "040000000")
+
+
+("grid"
+ "200001090"
+ "010030700"
+ "900800020"
+ "000000850"
+ "060400000"
+ "000070003"
+ "020300060"
+ "000500000"
+ "109000205")
+
+
+("grid"
+ "007008000"
+ "006020300"
+ "030000009"
+ "010050060"
+ "000010000"
+ "070900002"
+ "000000004"
+ "083004000"
+ "260000510")
+
+
+("grid"
+ "000360000"
+ "850000000"
+ "904008000"
+ "000006800"
+ "000000017"
+ "009004500"
+ "010500060"
+ "400009002"
+ "000003000")
+
+
+("grid"
+ "340600000"
+ "007000000"
+ "020080570"
+ "000005000"
+ "070010020"
+ "000400000"
+ "036020010"
+ "000000900"
+ "000007082")
+
+
+("grid"
+ "000000401"
+ "800200000"
+ "000607000"
+ "000800060"
+ "040000300"
+ "010000000"
+ "600000020"
+ "050010000"
+ "700030000")
+
+
+("grid"
+ "040050067"
+ "000100040"
+ "000200000"
+ "100800300"
+ "000000200"
+ "060000000"
+ "000040050"
+ "300000800"
+ "200000000")
+
+
+("grid"
+ "000000040"
+ "002004001"
+ "070050090"
+ "003007000"
+ "040060000"
+ "600100800"
+ "020000100"
+ "850900060"
+ "000080003")
+
+
+("grid"
+ "800700004"
+ "050000600"
+ "000000000"
+ "030970008"
+ "000043005"
+ "000020900"
+ "006000000"
+ "200060007"
+ "071008302")
+
+
+("grid"
+ "080004050"
+ "000700300"
+ "000000000"
+ "010085000"
+ "600000200"
+ "000040000"
+ "302600000"
+ "000000041"
+ "700000000")
+
+
+("grid"
+ "000070080"
+ "006000500"
+ "020003061"
+ "010007002"
+ "008005340"
+ "200900000"
+ "002000000"
+ "580006030"
+ "400010000")
+
+
+("grid"
+ "000000801"
+ "600200000"
+ "000705000"
+ "000600020"
+ "010000300"
+ "080000000"
+ "200000070"
+ "040080000"
+ "500030000")
+
+
+("grid"
+ "020000000"
+ "000600003"
+ "074080000"
+ "000003002"
+ "080040010"
+ "600500000"
+ "000010780"
+ "500009000"
+ "000000040")
+
+
+("grid"
+ "052006800"
+ "000007020"
+ "000000600"
+ "004800900"
+ "200410000"
+ "001000008"
+ "006100380"
+ "000090006"
+ "300600109")
+
+
+("grid"
+ "000010780"
+ "500009000"
+ "000000040"
+ "020000000"
+ "000600003"
+ "074080000"
+ "000003002"
+ "080040010"
+ "600500000")
+
+
+("grid"
+ "100000003"
+ "060300700"
+ "070005001"
+ "210700090"
+ "007000000"
+ "008010020"
+ "000806400"
+ "009020060"
+ "000400000")
+
+
+("grid"
+ "400070100"
+ "001904605"
+ "000001000"
+ "000700002"
+ "002030000"
+ "847006000"
+ "014000806"
+ "020000300"
+ "600090000")
+
+
+("grid"
+ "000000801"
+ "700200000"
+ "000506000"
+ "000700050"
+ "010000300"
+ "080000000"
+ "500000020"
+ "030080000"
+ "600040000")
+
+
+("grid"
+ "963000000"
+ "100008000"
+ "000205000"
+ "040800000"
+ "010000700"
+ "000030025"
+ "700000030"
+ "009020407"
+ "000000900")
+
+
+("grid"
+ "150300000"
+ "070040200"
+ "004072000"
+ "008000000"
+ "000900108"
+ "010080790"
+ "000003800"
+ "000000000"
+ "600007423")
+
+
+("grid"
+ "000000000"
+ "057240009"
+ "800009470"
+ "009003000"
+ "500900120"
+ "003010900"
+ "060000250"
+ "000560000"
+ "070000006")
+
+
+("grid"
+ "000075000"
+ "010020000"
+ "040003000"
+ "500000302"
+ "000800010"
+ "000000600"
+ "000100480"
+ "200000000"
+ "700000000")
+
+
+("grid"
+ "600000703"
+ "040800000"
+ "000000000"
+ "000504080"
+ "700200000"
+ "103000000"
+ "020000050"
+ "000070900"
+ "000010000")
+
+
+("grid"
+ "000060004"
+ "006030000"
+ "100400507"
+ "700000805"
+ "000800000"
+ "608000090"
+ "002090000"
+ "400003200"
+ "009700100")
+
+
+("grid"
+ "032000005"
+ "800300000"
+ "904280001"
+ "000400039"
+ "000600050"
+ "000010000"
+ "020006708"
+ "000004000"
+ "095000060")
+
+
+("grid"
+ "000503000"
+ "000060700"
+ "508000016"
+ "360020000"
+ "000401000"
+ "000030005"
+ "670000208"
+ "004070000"
+ "000200500")
+
+
+("grid"
+ "050307040"
+ "100000000"
+ "030000000"
+ "508030610"
+ "000800509"
+ "060010000"
+ "000040006"
+ "000692700"
+ "002000900")
+
+
+("grid"
+ "005008001"
+ "800000090"
+ "000000780"
+ "000400000"
+ "640000900"
+ "000053002"
+ "060000000"
+ "001380050"
+ "000907140")
+
+
+("grid"
+ "000000000"
+ "072060100"
+ "005100082"
+ "080001300"
+ "400000000"
+ "037090010"
+ "000023800"
+ "504009000"
+ "000000790")
+
+
+("grid"
+ "000658000"
+ "004000000"
+ "120000000"
+ "000009607"
+ "000300500"
+ "002080003"
+ "001900800"
+ "306000004"
+ "000047300")
+
+
+("grid"
+ "020300000"
+ "006008090"
+ "830500000"
+ "000200080"
+ "709005000"
+ "000006004"
+ "000000010"
+ "001000402"
+ "200700809")
+
+
+("grid"
+ "050090000"
+ "100000600"
+ "000308000"
+ "008040009"
+ "514000000"
+ "030000200"
+ "000000004"
+ "080006007"
+ "700150060")
+
+
+("grid"
+ "000002000"
+ "000070001"
+ "700300090"
+ "800700000"
+ "020890600"
+ "013006000"
+ "090050824"
+ "000008910"
+ "000000000")
+
+
+("grid"
+ "300080000"
+ "000700005"
+ "100000000"
+ "000000360"
+ "002004000"
+ "070000000"
+ "000060130"
+ "045200000"
+ "000000800")
+
+
diff --git a/src/ikarus.boot b/src/ikarus.boot
index cd2570d..8bfb891 100644
Binary files a/src/ikarus.boot and b/src/ikarus.boot differ
diff --git a/src/libtimers.ss b/src/libtimers.ss
new file mode 100644
index 0000000..44c46a3
--- /dev/null
+++ b/src/libtimers.ss
@@ -0,0 +1,58 @@
+
+(let ()
+  (define-record stats 
+    (user-secs user-usecs sys-secs sys-usecs real-secs real-usecs))
+
+  (define (mk-stats)
+    (make-stats #f #f #f #f #f #f))
+
+  (define (set-stats! t)
+    (foreign-call "ikrt_stats_now" t))
+
+  (define (print-stats message t1 t0)
+    (define (print-time msg secs usecs)
+      (if (fx< usecs 0)
+          (print-time msg (fx- secs 1) (fx+ usecs 1000000))
+          (printf "    ~a.~a~a~as ~a time\n"
+                  secs
+                  (fxremainder (fxquotient usecs 100000) 10)
+                  (fxremainder (fxquotient usecs 10000) 10)
+                  (fxremainder (fxquotient usecs 1000) 10)
+                  msg)))
+    (if message
+        (printf "running stats for ~a:\n" message)
+        (printf "running stats:\n"))
+    (print-time "user" 
+        (fx- (stats-user-secs t1) (stats-user-secs t0))
+        (fx- (stats-user-usecs t1) (stats-user-usecs t0)))
+    (print-time "system" 
+        (fx- (stats-sys-secs t1) (stats-sys-secs t0))
+        (fx- (stats-sys-usecs t1) (stats-sys-usecs t0)))
+    (print-time "real" 
+        (fx- (stats-real-secs t1) (stats-real-secs t0))
+        (fx- (stats-real-usecs t1) (stats-real-usecs t0))))
+
+  (define time-it
+    (case-lambda
+      [(proc) 
+       (time-it proc #f)]
+      [(proc message)
+       (unless (procedure? proc)
+         (error 'time-it "~s is not a procedure" proc))
+       (let* ([t1 (mk-stats)]
+              [t0 (mk-stats)])
+         (set-stats! t0)
+         (call-with-values proc
+           (case-lambda
+             [(v)
+              (set-stats! t1)
+              (print-stats message t1 t0)
+              v]
+             [v*
+              (set-stats! t1)
+              (print-stats message t1 t0)
+              (apply values v*)])))]))
+
+  (primitive-set! 'time-it time-it)
+  
+)
diff --git a/src/makefile.ss b/src/makefile.ss
index ad77e78..ebfefea 100755
--- a/src/makefile.ss
+++ b/src/makefile.ss
@@ -25,7 +25,8 @@
     syntax-case syntax-rules module $module import $import import-only
     syntax quasisyntax unsyntax unsyntax-splicing datum
     let let* let-values cond case define-record or and when unless do
-    include parameterize trace untrace trace-lambda trace-define))
+    include parameterize trace untrace trace-lambda trace-define
+    time))
 
 
 
@@ -84,6 +85,7 @@
     negative? zero? number->string logand = < > <= >=
     make-guardian weak-cons collect 
     interrupt-handler
+    time-it
     ))
 
 (define system-primitives
@@ -230,6 +232,7 @@
     ["libcafe.ss"       "libcafe.fasl"]
     ["libtrace.ss"      "libtrace.fasl"]
     ["libposix.ss"      "libposix.fasl"]
+    ["libtimers.ss"     "libtimers.fasl"]
     ["libtoplevel.ss"   "libtoplevel.fasl"]
     ))
 
diff --git a/src/psyntax-7.1.ss b/src/psyntax-7.1.ss
index 8a45f1d..0f2fc81 100644
--- a/src/psyntax-7.1.ss
+++ b/src/psyntax-7.1.ss
@@ -4669,3 +4669,9 @@
        #'(define id
            (make-traced-procedure 'id value))])))
 
+(define-syntax time
+  (lambda (x)
+    (syntax-case x ()
+      [(_ expr)
+       #'(time-it (lambda () expr) 'expr)])))
+