diff --git a/main.lua b/main.lua
index 02e4611..31e5759 100644
--- a/main.lua
+++ b/main.lua
@@ -62,6 +62,14 @@ for k,v in ipairs(colors) do
 	lgobjs[k]={c=k,super="lines"}
 	mgobjs[k]={c=k,super="color"}
 end
+local ltest=os.time()
+debug.sethook(function()
+	local lt=os.time()
+	if lt-ltest>4 then
+		print("!! we are in a freezer !!",debug.traceback())
+		ltest=lt
+	end
+end,"",1000)
 local cc=3
 local tt=0
 local bat=1
@@ -686,6 +694,7 @@ function love.mousemoved()
 end
 
 function love.update(dt)
+	ltest=os.time()
 	dt=math.min(dt,0.2)*(speeds[slow])
 	accumdt=math.min(1,accumdt+dt)
 	local fcc=0
@@ -695,22 +704,49 @@ function love.update(dt)
 		accumdt=accumdt-dt
 		if fcc>10 then return end
 		if running and playdbg then
-			for _=1,100 do	
-				local ix,iy=math.random(1,bw),math.random(1,bh)
-				local px,py=0,0
-				while px<1 or py<1 or px>bw or py>bh do
-					local ox,oy=unpack(({{1,0},{-1,0},{0,1},{0,-1}})[math.random(1,4)])
-					px,py=ix+ox,iy+oy
-				end
-				board[ix][iy],board[px][py]=
-				board[px][py],board[ix][iy]
-				local kills=check(ix,iy,check(px,py))
-				if kills and board[ix][iy] and board[px][py] then
-					megascan(ix,iy,board[ix][iy],megascan(px,py,board[px][py],kills))
-					killall(kills)
-				else
+			local gc=0
+			local tc=0
+			for x=1,bw do
+			for y=1,bh do
+				gc=gc+(board[x][y] and 1 or 0)
+				tc=tc+1
+			end end
+			if gc/tc>0.8 then
+				local goods={}
+				for _=1,1000 do
+					local ix,iy=math.random(1,bw),math.random(1,bh)
+					local px,py=0,0
+					while px<1 or py<1 or px>bw or py>bh do
+						local ox,oy=unpack(({{1,0},{-1,0},{0,1},{0,-1}})[math.random(1,4)])
+						px,py=ix+ox,iy+oy
+					end
 					board[ix][iy],board[px][py]=
 					board[px][py],board[ix][iy]
+					local kills=check(ix,iy,check(px,py))
+					local kc=0
+					for k,v in pairs(kills or {}) do
+						if v[3] and v[3].super=="color" then
+							kc=kc+50
+						elseif v[3] then
+							kc=kc+20
+						end
+						kc=kc+1
+					end
+					if kills and board[ix][iy] and board[px][py] then
+						goods[#goods+1]={ix,iy,px,py,kills,kc}
+					end
+					board[ix][iy],board[px][py]=
+					board[px][py],board[ix][iy]
+				end
+				table.sort(goods,function(a,b)
+					return a[6]>b[6]
+				end)
+				if #goods>0 then
+					local ix,iy,px,py,kills=unpack(goods[1])
+					board[ix][iy],board[px][py]=
+					board[px][py],board[ix][iy]
+					megascan(ix,iy,board[ix][iy],megascan(px,py,board[px][py],kills))
+					killall(kills)
 				end
 			end
 		end
@@ -820,7 +856,11 @@ function love.update(dt)
 			toplchi=plchint
 		end
 		local oam,obm,rm={},{},{}
+		local tt=os.clock()
+		local itc=0
 		for k,v in pairs(tk) do
+			itc=itc+1
+			if os.clock()-tt>2 then error("too long "..itc.."; #"..#tk) end 
 			local x,y=unpack(v)
 			check(x,y,rm,oam,obm)
 		end