diff --git a/include/libtorrent/piece_picker.hpp b/include/libtorrent/piece_picker.hpp
index bedddc1c0..d3520cdf2 100755
--- a/include/libtorrent/piece_picker.hpp
+++ b/include/libtorrent/piece_picker.hpp
@@ -92,12 +92,14 @@ namespace libtorrent
 
 		struct block_info
 		{
-			block_info(): num_downloads(0) {}
+			block_info(): num_downloads(0), requested(0), finished(0) {}
 			// the peer this block was requested or
 			// downloaded from
 			tcp::endpoint peer;
 			// the number of times this block has been downloaded
-			int num_downloads;
+			unsigned num_downloads:14;
+			unsigned requested:1;
+			unsigned finished:1;
 		};
 
 		// the peers that are downloading this piece
@@ -109,17 +111,15 @@ namespace libtorrent
 
 		struct downloading_piece
 		{
+			downloading_piece(): finished(0), requested(0) {}
 			piece_state_t state;
 
 			// the index of the piece
 			int index;
-			// each bit represents a block in the piece
-			// set to one if the block has been requested
-			std::bitset<max_blocks_per_piece> requested_blocks;
-			// the bit is set to one if the block has been acquired
-			std::bitset<max_blocks_per_piece> finished_blocks;
 			// info about each block
 			block_info info[max_blocks_per_piece];
+			boost::uint16_t finished;
+			boost::uint16_t requested;
 		};
 
 		piece_picker(int blocks_per_piece
diff --git a/include/libtorrent/storage.hpp b/include/libtorrent/storage.hpp
index 7c6eeecd3..5bf8c3991 100755
--- a/include/libtorrent/storage.hpp
+++ b/include/libtorrent/storage.hpp
@@ -51,6 +51,7 @@ POSSIBILITY OF SUCH DAMAGE.
 
 
 #include "libtorrent/torrent_info.hpp"
+#include "libtorrent/piece_picker.hpp"
 #include "libtorrent/config.hpp"
 
 namespace libtorrent
@@ -153,7 +154,7 @@ namespace libtorrent
 		unsigned long piece_crc(
 			int slot_index
 			, int block_size
-			, const std::bitset<256>& bitmask);
+			, piece_picker::block_info const* bi);
 		int slot_for_piece(int piece_index) const;
 
 		size_type read(
diff --git a/src/peer_connection.cpp b/src/peer_connection.cpp
index 33154ab7c..0d33acff9 100755
--- a/src/peer_connection.cpp
+++ b/src/peer_connection.cpp
@@ -995,7 +995,7 @@ namespace libtorrent
 				for (std::vector<piece_picker::downloading_piece>::const_iterator i =
 					dl_queue.begin(); i != dl_queue.end(); ++i)
 				{
-					assert(int(i->finished_blocks.count()) < blocks_per_piece);
+					assert(i->finished < blocks_per_piece);
 				}
 			}
 		}
diff --git a/src/piece_picker.cpp b/src/piece_picker.cpp
index bba6f0474..d8d157c59 100755
--- a/src/piece_picker.cpp
+++ b/src/piece_picker.cpp
@@ -117,7 +117,7 @@ namespace libtorrent
 				tcp::endpoint peer;
 				for (int j = 0; j < m_blocks_per_piece; ++j)
 				{
-					if (i->finished_blocks[j])
+					if (i->info[j].finished)
 						mark_as_finished(piece_block(i->index, j), peer);
 				}
 				if (is_piece_finished(i->index))
@@ -210,20 +210,27 @@ namespace libtorrent
 		{
 			bool blocks_requested = false;
 			int num_blocks = blocks_in_piece(i->index);
+			int num_requested = 0;
+			int num_finished = 0;
 			for (int k = 0; k < num_blocks; ++k)
 			{
-				if (i->finished_blocks[k])
+				if (i->info[k].finished)
 				{
-					assert(i->requested_blocks[k]);
+					++num_finished;
+					assert(i->info[k].requested);
+					++num_requested;
 					continue;
 				}
-				if (i->requested_blocks[k])
+				if (i->info[k].requested)
 				{
+					++num_requested;
 					blocks_requested = true;
-					break;
 				}
 			}
 			assert(blocks_requested == (i->state != none));
+			assert(num_requested == i->requested);
+			assert(num_finished == i->finished);
+			assert(num_finished <= num_requested);
 		}
 
 
@@ -1010,10 +1017,11 @@ namespace libtorrent
 		{
 			for (int j = 0; j < num_blocks_in_piece; ++j)
 			{
-				if ((p.finished_blocks[j] == 1
-					|| p.requested_blocks[j] == 1)
-					&& p.info[j].peer != peer
-					&& p.info[j].peer != tcp::endpoint())
+				piece_picker::block_info const& info = p.info[j];
+				if ((info.finished == 1
+					|| info.requested == 1)
+					&& info.peer != peer
+					&& info.peer != tcp::endpoint())
 				{
 					return false;
 				}
@@ -1065,9 +1073,10 @@ namespace libtorrent
 					if (int(backup_blocks.size()) >= num_blocks) continue;
 					for (int j = 0; j < num_blocks_in_piece; ++j)
 					{
-						if (p->finished_blocks[j] == 1) continue;
-						if (p->requested_blocks[j] == 1
-							&& p->info[j].peer == peer) continue;
+						block_info const& info = p->info[j];
+						if (info.finished) continue;
+						if (info.requested
+							&& info.peer == peer) continue;
 						backup_blocks.push_back(piece_block(*i, j));
 					}
 					continue;
@@ -1076,10 +1085,10 @@ namespace libtorrent
 				for (int j = 0; j < num_blocks_in_piece; ++j)
 				{
 					// ignore completed blocks
-					if (p->finished_blocks[j] == 1) continue;
+					block_info const& info = p->info[j];
+					if (info.finished) continue;
 					// ignore blocks requested from this peer already
-					if (p->requested_blocks[j] == 1
-						&& p->info[j].peer == peer) continue;
+					if (info.requested && info.peer == peer) continue;
 					// if the piece is fast and the peer is slow, or vice versa,
 					// add the block as a backup.
 					// override this behavior if all the other blocks
@@ -1102,7 +1111,7 @@ namespace libtorrent
 					// blocks that have not been requested from any
 					// other peer.
 					interesting_blocks.push_back(piece_block(*i, j));
-					if (p->requested_blocks[j] == 0)
+					if (p->info[j].requested == 0)
 					{
 						// we have found a block that's free to download
 						num_blocks--;
@@ -1146,11 +1155,11 @@ namespace libtorrent
 		std::vector<downloading_piece>::const_iterator i
 			= std::find_if(m_downloads.begin(), m_downloads.end(), has_index(index));
 		assert(i != m_downloads.end());
-		assert((int)i->finished_blocks.count() <= m_blocks_per_piece);
+		assert((int)i->finished <= m_blocks_per_piece);
 		int max_blocks = blocks_in_piece(index);
-		if ((int)i->finished_blocks.count() < max_blocks) return false;
+		if ((int)i->finished < max_blocks) return false;
 
-		assert((int)i->requested_blocks.count() == max_blocks);
+		assert((int)i->requested == max_blocks);
 		return true;
 	}
 
@@ -1169,7 +1178,7 @@ namespace libtorrent
 				, has_index(block.piece_index));
 
 		assert(i != m_downloads.end());
-		return i->requested_blocks[block.block_index];
+		return i->info[block.block_index].requested;
 	}
 
 	bool piece_picker::is_finished(piece_block block) const
@@ -1184,7 +1193,7 @@ namespace libtorrent
 		std::vector<downloading_piece>::const_iterator i
 			= std::find_if(m_downloads.begin(), m_downloads.end(), has_index(block.piece_index));
 		assert(i != m_downloads.end());
-		return i->finished_blocks[block.block_index];
+		return i->info[block.block_index].finished;
 	}
 
 
@@ -1208,8 +1217,10 @@ namespace libtorrent
 			downloading_piece dp;
 			dp.state = state;
 			dp.index = block.piece_index;
-			dp.requested_blocks[block.block_index] = 1;
-			dp.info[block.block_index].peer = peer;
+			block_info& info = dp.info[block.block_index];
+			info.requested = 1;
+			info.peer = peer;
+			++dp.requested;
 			m_downloads.push_back(dp);
 		}
 		else
@@ -1217,9 +1228,11 @@ namespace libtorrent
 			std::vector<downloading_piece>::iterator i
 				= std::find_if(m_downloads.begin(), m_downloads.end(), has_index(block.piece_index));
 			assert(i != m_downloads.end());
-			assert(i->requested_blocks[block.block_index] == 0);
-			i->info[block.block_index].peer = peer;
-			i->requested_blocks[block.block_index] = 1;
+			block_info& info = i->info[block.block_index];
+			assert(info.requested == 0);
+			info.peer = peer;
+			info.requested = 1;
+			++i->requested;
 			if (i->state == none) i->state = state;
 		}
 	}
@@ -1245,8 +1258,11 @@ namespace libtorrent
 			downloading_piece dp;
 			dp.state = none;
 			dp.index = block.piece_index;
-			dp.requested_blocks[block.block_index] = 1;
-			dp.finished_blocks[block.block_index] = 1;
+			block_info& info = dp.info[block.block_index];
+			info.requested = 1;
+			info.finished = 1;
+			++dp.requested;
+			++dp.finished;
 			dp.info[block.block_index].peer = peer;
 			m_downloads.push_back(dp);
 		}
@@ -1255,25 +1271,14 @@ namespace libtorrent
 			std::vector<downloading_piece>::iterator i
 				= std::find_if(m_downloads.begin(), m_downloads.end(), has_index(block.piece_index));
 			assert(i != m_downloads.end());
-			i->info[block.block_index].peer = peer;
-			i->requested_blocks[block.block_index] = 1;
-			i->finished_blocks[block.block_index] = 1;
+			block_info& info = i->info[block.block_index];
+			info.peer = peer;
+			if (!info.requested) ++i->requested;
+			info.requested = 1;
+			if (!info.finished) ++i->finished;
+			info.finished = 1;
 
-			// TODO: maintain requested and finished counters so that
-			// we don't have to count every time
-			bool blocks_requested = false;
-			int num_blocks = blocks_in_piece(i->index);
-			for (int k = 0; k < num_blocks; ++k)
-			{
-				if (i->finished_blocks[k]) continue;
-				if (i->requested_blocks[k])
-				{
-					blocks_requested = true;
-					break;
-				}
-			}
-
-			if (!blocks_requested)
+			if (i->requested == i->finished)
 			{
 				// there are no blocks requested in this piece.
 				// remove the fast/slow state from it
@@ -1309,8 +1314,8 @@ namespace libtorrent
 		assert(block.block_index < max_blocks_per_piece);
 		assert(block.block_index >= 0);
 
-		if (i->requested_blocks[block.block_index] == false
-			|| i->finished_blocks[block.block_index] == true)
+		if (i->info[block.block_index].requested == false
+			|| i->info[block.block_index].requested == true)
 			return boost::optional<tcp::endpoint>();
 
 		return boost::optional<tcp::endpoint>(i->info[block.block_index].peer);
@@ -1336,26 +1341,27 @@ namespace libtorrent
 			, m_downloads.end(), has_index(block.piece_index));
 		assert(i != m_downloads.end());
 
-		if (i->finished_blocks[block.block_index])
+		if (i->info[block.block_index].finished)
 		{
-			assert(i->requested_blocks[block.block_index]);
+			assert(i->info[block.block_index].requested);
 			assert(std::find_if(m_downloads.begin(), m_downloads.end()
 				, has_index(block.piece_index)) == m_downloads.end());
 			return;
 		}
 
 		assert(block.block_index < blocks_in_piece(block.piece_index));
-		assert(i->requested_blocks[block.block_index]);
+		assert(i->info[block.block_index].requested);
 
 		// clear this block as being downloaded
-		i->requested_blocks[block.block_index] = false;
+		i->info[block.block_index].requested = false;
+		--i->requested;
 		
 		// clear the downloader of this block
 		i->info[block.block_index].peer = tcp::endpoint();
 
 		// if there are no other blocks in this piece
 		// that's being downloaded, remove it from the list
-		if (i->requested_blocks.count() == 0)
+		if (i->requested == 0)
 		{
 			m_downloads.erase(i);
 			piece_pos& p = m_piece_map[block.piece_index];
@@ -1366,28 +1372,11 @@ namespace libtorrent
 			assert(std::find_if(m_downloads.begin(), m_downloads.end()
 				, has_index(block.piece_index)) == m_downloads.end());
 		}
-		else
+		else if (i->requested == i->finished)
 		{
-			// TODO: maintain requested and finished counters so that
-			// we don't have to count every time
-			bool blocks_requested = false;
-			int num_blocks = blocks_in_piece(i->index);
-			for (int k = 0; k < num_blocks; ++k)
-			{
-				if (i->finished_blocks[k]) continue;
-				if (i->requested_blocks[k])
-				{
-					blocks_requested = true;
-					break;
-				}
-			}
-
-			if (!blocks_requested)
-			{
-				// there are no blocks requested in this piece.
-				// remove the fast/slow state from it
-				i->state = none;
-			}
+			// there are no blocks requested in this piece.
+			// remove the fast/slow state from it
+			i->state = none;
 		}
 	}
 
@@ -1397,7 +1386,7 @@ namespace libtorrent
 		for (std::vector<downloading_piece>::const_iterator i = m_downloads.begin();
 			i != m_downloads.end(); ++i)
 		{
-			counter += (int)i->finished_blocks.count();
+			counter += (int)i->finished;
 		}
 		return counter;
 	}
diff --git a/src/session_impl.cpp b/src/session_impl.cpp
index 253ddfa6f..11b2ce8aa 100755
--- a/src/session_impl.cpp
+++ b/src/session_impl.cpp
@@ -1906,11 +1906,14 @@ namespace libtorrent { namespace detail
 						{
 							const int bit = j * 8 + k;
 							if (bits & (1 << k))
-								p.finished_blocks[bit] = true;
+							{
+								p.info[bit].finished = true;
+								++p.finished;
+							}
 						}
 					}
 
-					if (p.finished_blocks.count() == 0) continue;
+					if (p.finished == 0) continue;
 	
 					std::vector<int>::iterator slot_iter
 						= std::find(tmp_pieces.begin(), tmp_pieces.end(), p.index);
@@ -1929,7 +1932,7 @@ namespace libtorrent { namespace detail
 						= torrent_ptr->filesystem().piece_crc(
 							slot_index
 							, torrent_ptr->block_size()
-							, p.finished_blocks);
+							, p.info);
 
 					const entry& ad = (*i)["adler32"];
 	
diff --git a/src/storage.cpp b/src/storage.cpp
index 4aa4b014c..8e7ec6713 100755
--- a/src/storage.cpp
+++ b/src/storage.cpp
@@ -959,7 +959,7 @@ namespace libtorrent
 		unsigned long piece_crc(
 			int slot_index
 			, int block_size
-			, const std::bitset<256>& bitmask);
+			, piece_picker::block_info const* bi);
 
 		int slot_for_piece(int piece_index) const;
 
@@ -1208,15 +1208,15 @@ namespace libtorrent
 	unsigned long piece_manager::piece_crc(
 		int index
 		, int block_size
-		, const std::bitset<256>& bitmask)
+		, piece_picker::block_info const* bi)
 	{
-		return m_pimpl->piece_crc(index, block_size, bitmask);
+		return m_pimpl->piece_crc(index, block_size, bi);
 	}
 
 	unsigned long piece_manager::impl::piece_crc(
 		int slot_index
 		, int block_size
-		, const std::bitset<256>& bitmask)
+		, piece_picker::block_info const* bi)
 	{
 		assert(slot_index >= 0);
 		assert(slot_index < m_info.num_pieces());
@@ -1230,7 +1230,7 @@ namespace libtorrent
 
 		for (int i = 0; i < num_blocks-1; ++i)
 		{
-			if (!bitmask[i]) continue;
+			if (!bi[i].finished) continue;
 			m_storage->read(
 				&buf[0]
 				, slot_index
@@ -1238,7 +1238,7 @@ namespace libtorrent
 				, block_size);
 			crc.update(&buf[0], block_size);
 		}
-		if (bitmask[num_blocks - 1])
+		if (bi[num_blocks - 1].finished)
 		{
 			m_storage->read(
 				&buf[0]
@@ -1260,7 +1260,8 @@ namespace libtorrent
 		assert(offset >= 0);
 		assert(size > 0);
 		assert(piece_index >= 0 && piece_index < (int)m_piece_to_slot.size());
-		assert(m_piece_to_slot[piece_index] >= 0 && m_piece_to_slot[piece_index] < (int)m_slot_to_piece.size());
+		assert(m_piece_to_slot[piece_index] >= 0
+			&& m_piece_to_slot[piece_index] < (int)m_slot_to_piece.size());
 		int slot = m_piece_to_slot[piece_index];
 		assert(slot >= 0 && slot < (int)m_slot_to_piece.size());
 		return m_storage->read(buf, slot, offset, size);
diff --git a/src/torrent.cpp b/src/torrent.cpp
index ebc2d9f67..ebadd35a7 100755
--- a/src/torrent.cpp
+++ b/src/torrent.cpp
@@ -738,8 +738,7 @@ namespace libtorrent
 			int corr = 0;
 			int index = i->index;
 			assert(!m_have_pieces[index]);
-			assert(int(i->finished_blocks.count())
-				< m_picker->blocks_in_piece(index));
+			assert(i->finished < m_picker->blocks_in_piece(index));
 
 #ifndef NDEBUG
 			for (std::vector<piece_picker::downloading_piece>::const_iterator j = boost::next(i);
@@ -751,17 +750,17 @@ namespace libtorrent
 
 			for (int j = 0; j < blocks_per_piece; ++j)
 			{
-				assert(i->finished_blocks[j] == 0 || i->finished_blocks[j] == 1);
-				assert(m_picker->is_finished(piece_block(index, j)) == i->finished_blocks[j]);
-				corr += i->finished_blocks[j] * m_block_size;
+				assert(i->info[j].finished == 0 || i->info[j].finished == 1);
+				assert(m_picker->is_finished(piece_block(index, j)) == i->info[j].finished);
+				corr += i->info[j].finished * m_block_size;
 				assert(index != last_piece || j < m_picker->blocks_in_last_piece()
-					|| i->finished_blocks[j] == 0);
+					|| i->info[j].finished == 0);
 			}
 
 			// correction if this was the last piece
 			// and if we have the last block
 			if (i->index == last_piece
-				&& i->finished_blocks[m_picker->blocks_in_last_piece()-1])
+				&& i->info[m_picker->blocks_in_last_piece()-1].finished)
 			{
 				corr -= m_block_size;
 				corr += m_torrent_file.piece_size(last_piece) % m_block_size;
@@ -836,7 +835,7 @@ namespace libtorrent
 				std::cerr << "   " << i->index << " ";
 				for (int j = 0; j < blocks_per_piece; ++j)
 				{
-					std::cerr << i->finished_blocks[j];
+					std::cerr << i->info[j].finished;
 				}
 				std::cerr << std::endl;
 			}
diff --git a/src/torrent_handle.cpp b/src/torrent_handle.cpp
index dfdccf86e..4e8dff66c 100755
--- a/src/torrent_handle.cpp
+++ b/src/torrent_handle.cpp
@@ -542,7 +542,7 @@ namespace libtorrent
 			for (std::vector<piece_picker::downloading_piece>::const_iterator i
 				= q.begin(); i != q.end(); ++i)
 			{
-				if (i->finished_blocks.count() == 0) continue;
+				if (i->finished == 0) continue;
 
 				entry piece_struct(entry::dictionary_t);
 
@@ -557,7 +557,7 @@ namespace libtorrent
 				{
 					unsigned char v = 0;
 					for (int k = 0; k < 8; ++k)
-						v |= i->finished_blocks[j*8+k]?(1 << k):0;
+						v |= i->info[j*8+k].finished?(1 << k):0;
 					bitmask.insert(bitmask.end(), v);
 				}
 				piece_struct["bitmask"] = bitmask;
@@ -567,7 +567,7 @@ namespace libtorrent
 					= t->filesystem().piece_crc(
 						t->filesystem().slot_for_piece(i->index)
 						, t->block_size()
-						, i->finished_blocks);
+						, i->info);
 
 				piece_struct["adler32"] = adler;
 
@@ -769,12 +769,12 @@ namespace libtorrent
 		{
 			partial_piece_info pi;
 			pi.piece_state = (partial_piece_info::state_t)i->state;
-			pi.finished_blocks = i->finished_blocks;
-			pi.requested_blocks = i->requested_blocks;
 			for (int j = 0; j < partial_piece_info::max_blocks_per_piece; ++j)
 			{
 				pi.peer[j] = i->info[j].peer;
 				pi.num_downloads[j] = i->info[j].num_downloads;
+				pi.finished_blocks[j] = i->info[j].finished;
+				pi.requested_blocks[j] = i->info[j].requested;
 			}
 			pi.piece_index = i->index;
 			pi.blocks_in_piece = p.blocks_in_piece(i->index);