diff --git a/TODO b/TODO
index 3b339cb2..6b0b20e3 100644
--- a/TODO
+++ b/TODO
@@ -1,3 +1,86 @@
+- overlap doesn't seem to work
+
+- check operations called in sharpen, we seem to have some gaps, looking at the
+  trace
+
+- try disabling turbo-boost?
+
+- calculate unk% from total time - (work time + wait time)
+
+
+
+git master, -o2, --enable-debug=no
+
+$ time vips sharpen k2.jpg x.jpg --radius 20 --vips-concurrency=1
+real	0m1.404s
+user	0m1.419s
+sys	0m0.023s
+
+$ time vips sharpen k2.jpg x.jpg --radius 20 --vips-concurrency=2
+real	0m0.870s
+user	0m1.659s
+sys	0m0.036s
+
+$ time vips sharpen k2.jpg x.jpg --radius 20
+real	0m0.760s
+user	0m2.726s
+sys	0m0.069s
+
+two cores gets a 1.404 / 0.870 = 1.61x speedup
+
+turbo-boost is 20%, so if 1 core were 20% slower, it'd be 1.685
+
+1.685 / 0.870 = 1.94x speedup
+
+(check this, use MHz in tubo and non-turbo)
+
+for four threads, we add 2.726 - 1.659 = 1.067 cpu but only get another 15%
+off the wall-clock time
+
+john@bambam ~/pics $ time vips sharpen k2.jpg x.jpg --radius 20 --vips-profile
+recording profile in vips-profile.txt
+real	0m0.758s
+user	0m2.768s
+sys	0m0.032s
+john@bambam ~/pics $ vipsprofile 
+reading from vips-profile.txt
+loaded 5885 events
+last time = 0.710619
+name				alive	wait%	work%	unk%
+     worker (0x7f66000008c0) 0	0.0003	67.7	0	32.3
+     worker (0x7f66100008c0) 1	0.00037	37.2	0	62.8
+     worker (0x7f66080008c0) 2	0.00032	93.5	0	6.54
+     worker (0x7f660c0008c0) 3	0.00033	86.8	0	13.2
+     worker (0x7f66080008c0) 4	0.00023	63.8	0	36.2
+     worker (0x7f661000a360) 5	0.00024	96.7	0	3.33
+     worker (0x7f660c0008c0) 6	0.00042	78.1	0	21.9
+     worker (0x7f66000012d0) 7	0.00025	85	0	15
+     worker (0x7f660c011450) 8	0.0001	30.7	0	69.3
+     worker (0x7f661000a360) 9	0.00011	89.7	0	10.3
+    worker (0x7f6608011850) 10	0.00012	93.2	0	6.78
+    worker (0x7f66000012d0) 11	0.00023	14.1	8.55	77.4
+    worker (0x7f661000a360) 12	0.00013	47.2	0	52.8
+    worker (0x7f6608011850) 13	0.00011	91.2	0	8.77
+    worker (0x7f660c011430) 14	0.00015	12.9	0	87.1
+    worker (0x7f6600009fa0) 15	0.00019	45.7	0	54.3
+    worker (0x7f660c011450) 16	0.00011	90.4	0	9.65
+    worker (0x7f6600009f80) 17	0.00017	5.81	4.65	89.5
+    worker (0x7f661000a1f0) 18	0.00013	93.6	0	6.4
+    worker (0x7f6608011850) 19	0.00011	35.8	0	64.2
+    worker (0x7f65fc0008c0) 20	  0.69	0.453	95.7	3.83
+    worker (0x7f65f80008c0) 21	  0.69	0.333	96.9	2.75
+    worker (0x7f660c011450) 22	  0.69	0.288	97.1	2.57
+    worker (0x7f661000a1f0) 23	  0.69	0.127	97.2	2.63
+   wbuffer (0x7f66000011c0) 24	   0.7	98	0	1.98
+   wbuffer (0x7f660800fcd0) 25	   0.7	97.7	0	2.32
+           main (0x1e7e200) 26	  0.74	93.7	0	6.31
+writing to vips-profile.svg
+
+
+
+
+
+
 - seen some leaks from 
 
 	vips dzsave --layout google wtc.jpg x