diff --git a/include/library/workthread.hpp b/include/library/workthread.hpp
index bcce5b47..736bf3e0 100644
--- a/include/library/workthread.hpp
+++ b/include/library/workthread.hpp
@@ -85,6 +85,14 @@ public:
  * Note: Don't call from outside workthread code.
  */
 	int operator()(int dummy);
+/**
+ * Get wait counters.
+ *
+ * Retrns: Two-element tuple.
+ *	- The first element is the amount of microseconds wait_busy() has waited.
+ *	- The second element is the amount of microseconds wait_workflag() has waited.
+ */
+	std::pair<uint64_t, uint64_t> get_wait_count();
 protected:
 /**
  * Thread entrypoint.
@@ -106,6 +114,8 @@ private:
 	volatile bool busy;
 	volatile bool exception_caught;
 	volatile bool exception_oom;
+	volatile uint64_t waitamt_busy;
+	volatile uint64_t waitamt_work;
 	std::string exception_text;
 };
 
diff --git a/include/video/avi/codec.hpp b/include/video/avi/codec.hpp
index 8abc3c5e..c8046e08 100644
--- a/include/video/avi/codec.hpp
+++ b/include/video/avi/codec.hpp
@@ -94,6 +94,13 @@ struct avi_video_codec
  * Returns: The packet.
  */
 	virtual avi_packet getpacket() = 0;
+/**
+ * Send performance counters.
+ *
+ * Parameter b: Amount of busywaiting by emulator.
+ * Parameter w: Amount of workwaiting by dumper.
+ */
+	virtual void send_performance_counters(uint64_t b, uint64_t w);
 };
 
 /**
diff --git a/src/library/workthread.cpp b/src/library/workthread.cpp
index 6afab0a2..ab3aeb91 100644
--- a/src/library/workthread.cpp
+++ b/src/library/workthread.cpp
@@ -1,5 +1,16 @@
 #include "library/workthread.hpp"
 #include <stdexcept>
+#include <sys/time.h>
+
+namespace
+{
+	uint64_t ticks()
+	{
+		struct timeval tv;
+		gettimeofday(&tv, NULL);
+		return static_cast<uint64_t>(tv.tv_sec) * 1000000 + tv.tv_usec;
+	}
+}
 
 struct worker_thread_reflector
 {
@@ -15,6 +26,8 @@ worker_thread::worker_thread()
 	reflector = NULL;
 	workflag = 0;
 	busy = false;
+	waitamt_busy = 0;
+	waitamt_work = 0;
 	exception_caught = false;
 	exception_oom = false;
 	joined = false;
@@ -58,8 +71,12 @@ void worker_thread::clear_busy()
 void worker_thread::wait_busy()
 {
 	umutex_class h(mutex);
-	while(busy)
-		condition.wait(h);
+	if(busy) {
+		uint64_t tmp = ticks();
+		while(busy)
+			condition.wait(h);
+		waitamt_busy += (ticks() - tmp);
+	}
 }
 
 void worker_thread::rethrow()
@@ -90,11 +107,21 @@ uint32_t worker_thread::clear_workflag(uint32_t flag)
 uint32_t worker_thread::wait_workflag()
 {
 	umutex_class h(mutex);
-	while(!workflag)
-		condition.wait(h);
+	if(!workflag) {
+		uint64_t tmp = ticks();
+		while(!workflag)
+			condition.wait(h);
+		waitamt_work += (ticks() - tmp);
+	}
 	return workflag;
 }
 
+std::pair<uint64_t, uint64_t> worker_thread::get_wait_count()
+{
+	umutex_class h(mutex);
+	return std::make_pair(waitamt_busy, waitamt_work);
+}
+
 int worker_thread::operator()(int dummy)
 {
 	try {
diff --git a/src/video/avi.cpp b/src/video/avi.cpp
index 297447f3..632bbe5c 100644
--- a/src/video/avi.cpp
+++ b/src/video/avi.cpp
@@ -127,6 +127,7 @@ namespace
 		uint32_t segframes;
 		uint32_t max_segframes;
 		bool closed;
+		avi_video_codec* ivcodec;
 	};
 
 #define WORKFLAG_QUEUE_FRAME 1
@@ -137,6 +138,7 @@ namespace
 	avi_worker::avi_worker(const struct avi_info& info)
 		: aviout(info.prefix, *info.vcodec, *info.acodec, info.sample_rate, info.audio_chans)
 	{
+		ivcodec = info.vcodec;
 		segframes = 0;
 		max_segframes = info.max_frames;
 		fire();
@@ -183,6 +185,8 @@ namespace
 				f.force_break = (segframes == max_segframes && max_segframes > 0);
 				if(f.force_break)
 					segframes = 0;
+				auto wc = get_wait_count();
+				ivcodec->send_performance_counters(wc.first, wc.second);
 				memcpy(&f.data[0], frame, 4 * frame_width * frame_height);
 				frame = NULL;
 				clear_workflag(WORKFLAG_QUEUE_FRAME);
diff --git a/src/video/avi/codec.cpp b/src/video/avi/codec.cpp
index 00660597..e8bb1527 100644
--- a/src/video/avi/codec.cpp
+++ b/src/video/avi/codec.cpp
@@ -22,6 +22,10 @@ avi_video_codec::format::format(uint32_t _width, uint32_t _height, uint32_t _com
 	clr_important = 0;
 }
 
+void avi_video_codec::send_performance_counters(uint64_t b, uint64_t w)
+{
+}
+
 avi_audio_codec::format::format(uint16_t tag)
 {
 	max_bytes_per_sec = 200000;