diff --git a/include/libtorrent/disk_buffer_pool.hpp b/include/libtorrent/disk_buffer_pool.hpp
index 7cc605f27..2d93c0f22 100644
--- a/include/libtorrent/disk_buffer_pool.hpp
+++ b/include/libtorrent/disk_buffer_pool.hpp
@@ -49,7 +49,7 @@ POSSIBILITY OF SUCH DAMAGE.
 #endif
 
 #if defined TORRENT_DEBUG || TORRENT_RELEASE_ASSERTS || TORRENT_DISK_STATS
-#include <map>
+#include <boost/unordered_map.hpp>
 #endif
 
 namespace libtorrent
@@ -129,8 +129,8 @@ namespace libtorrent
 	public:
 		void rename_buffer(char* buf, char const* category);
 	protected:
-		std::map<std::string, int> m_categories;
-		std::map<char*, std::string> m_buf_to_category;
+		boost::unordered_map<std::string, int> m_categories;
+		boost::unordered_map<char*, std::string> m_buf_to_category;
 		std::ofstream m_log;
 	private:
 #endif
diff --git a/src/peer_connection.cpp b/src/peer_connection.cpp
index 796c5af49..237ebe617 100644
--- a/src/peer_connection.cpp
+++ b/src/peer_connection.cpp
@@ -5883,6 +5883,7 @@ namespace libtorrent
 //					num_requests[i->block].peers.push_back(&p);
 				}
 			}
+			piece_picker::downloading_piece last_piece;
 			for (std::map<piece_block, peer_count_t>::iterator i = num_requests.begin()
 				, end(num_requests.end()); i != end; ++i)
 			{
@@ -5893,12 +5894,18 @@ namespace libtorrent
 				int count_with_nowant = pc.num_peers_with_nowant;
 				(void)count_with_timeouts;
 				(void)count_with_nowant;
-				int picker_count = t->picker().num_peers(b);
-				if (!t->picker().is_downloaded(b))
+				if (b.piece_index != last_piece.index)
+					t->picker().piece_info(b.piece_index, last_piece);
+
+				// has b been downloaded?
+				if ((last_piece.finished == 0 && last_piece.writing == 0)
+					|| (last_piece.info && last_piece.info[b.block_index].state >= piece_picker::block_info::state_writing))
+				{
+					int picker_count = t->picker().num_peers(b);
 					TORRENT_ASSERT(picker_count == count);
+				}
 			}
 		}
-#ifdef TORRENT_EXPENSIVE_INVARIANT_CHECKS
 		if (m_peer_info && type() == bittorrent_connection)
 		{
 			policy::const_iterator i = t->get_policy().begin_peer();
@@ -5909,7 +5916,6 @@ namespace libtorrent
 			}
 			TORRENT_ASSERT(i != end);
 		}
-#endif
 		if (t->has_picker() && !t->is_aborted())
 		{
 			// make sure that pieces that have completed the download
@@ -5930,17 +5936,6 @@ namespace libtorrent
 					complete = false;
 					break;
 				}
-/*
-// this invariant is not valid anymore since the completion event
-// might be queued in the io service
-				if (complete && !piece_failed)
-				{
-					disk_io_job ret = m_ses.m_disk_thread.find_job(
-						&t->filesystem(), -1, i->index);
-					TORRENT_ASSERT(ret.action == disk_io_job::hash || ret.action == disk_io_job::write);
-					TORRENT_ASSERT(ret.piece == i->index);
-				}
-*/
 			}
 		}
 
diff --git a/src/piece_picker.cpp b/src/piece_picker.cpp
index 326b34975..5eeb60936 100644
--- a/src/piece_picker.cpp
+++ b/src/piece_picker.cpp
@@ -142,7 +142,7 @@ namespace libtorrent
 	void piece_picker::piece_info(int index, piece_picker::downloading_piece& st) const
 	{
 #ifdef TORRENT_EXPENSIVE_INVARIANT_CHECKS
-		TORRENT_PIECE_PICKER_INVARIANT_CHECK;
+//		TORRENT_PIECE_PICKER_INVARIANT_CHECK;
 #endif
 		
 		TORRENT_ASSERT(index >= 0);
@@ -153,7 +153,7 @@ namespace libtorrent
 			std::vector<downloading_piece>::const_iterator piece = find_dl_piece(index);
 			TORRENT_ASSERT(piece != m_downloads.end());
 			st = *piece;
-			st.info = 0;
+//			st.info = 0;
 			return;
 		}
 		st.info = 0;
diff --git a/test/test_utp.cpp b/test/test_utp.cpp
index 1bda1edd8..7620d8869 100644
--- a/test/test_utp.cpp
+++ b/test/test_utp.cpp
@@ -100,7 +100,7 @@ void test_transfer()
 
 	create_directory("./tmp1_utp", ec);
 	std::ofstream file("./tmp1_utp/temporary");
-	boost::intrusive_ptr<torrent_info> t = ::create_torrent(&file, 512 * 1024, 20, false);
+	boost::intrusive_ptr<torrent_info> t = ::create_torrent(&file, 128 * 1024, 6, false);
 	file.close();
 
 	// for performance testing