diff --git a/nselib/dnsbl.lua b/nselib/dnsbl.lua
index 5f403c5d2..7b3b33b03 100644
--- a/nselib/dnsbl.lua
+++ b/nselib/dnsbl.lua
@@ -694,10 +694,12 @@ Helper = {
 		end
 
 		repeat
-			condvar "wait"
 			for t in pairs(threads) do
 				if ( coroutine.status(t) == "dead" ) then threads[t] = nil end
 			end
+			if ( next(threads) ) then
+				condvar "wait"
+			end
 		until( next(threads) == nil )
 		
 		for name, answer in pairs(answers) do
diff --git a/scripts/broadcast-dhcp-discover.nse b/scripts/broadcast-dhcp-discover.nse
index 7b45f8461..234de1bf4 100644
--- a/scripts/broadcast-dhcp-discover.nse
+++ b/scripts/broadcast-dhcp-discover.nse
@@ -192,10 +192,12 @@ action = function()
 	
 	-- wait until all threads are done
 	repeat 
-		condvar "wait"
 		for thread in pairs(threads) do
 			if coroutine.status(thread) == "dead" then threads[thread] = nil end
 		end
+		if ( next(threads) ) then
+			condvar "wait"
+		end
 	until next(threads) == nil
 	
 	local response = {}
diff --git a/scripts/broadcast-dhcp6-discover.nse b/scripts/broadcast-dhcp6-discover.nse
index 09f0a2c11..71eaf5fc4 100644
--- a/scripts/broadcast-dhcp6-discover.nse
+++ b/scripts/broadcast-dhcp6-discover.nse
@@ -104,12 +104,14 @@ action = function(host, port)
 	
 	-- wait until the probes are all done
 	repeat
-		condvar "wait"
 		for thread in pairs(threads) do
 			if coroutine.status(thread) == "dead" then
 				threads[thread] = nil
 			end
 		end
+		if ( next(threads) ) then
+			condvar "wait"
+		end
 	until next(threads) == nil
 
 	return stdnse.format_output(true, result)
diff --git a/scripts/broadcast-eigrp-discovery.nse b/scripts/broadcast-eigrp-discovery.nse
index 30130f375..9d6f78732 100644
--- a/scripts/broadcast-eigrp-discovery.nse
+++ b/scripts/broadcast-eigrp-discovery.nse
@@ -251,10 +251,12 @@ action = function()
 	local condvar = nmap.condvar(astab)
 	-- Wait for the listening threads to finish
 	repeat
-	    condvar("wait")
-	    for thread in pairs(lthreads) do
-		if coroutine.status(thread) == "dead" then lthreads[thread] = nil end
-	    end
+		for thread in pairs(lthreads) do
+			if coroutine.status(thread) == "dead" then lthreads[thread] = nil end
+	  end
+		if ( next(lthreads) ) then
+			condvar("wait")
+		end
 	until next(lthreads) == nil;
 
 	if #astab > 0 then
diff --git a/scripts/broadcast-igmp-discovery.nse b/scripts/broadcast-igmp-discovery.nse
index cf8b3be07..8d4d13712 100644
--- a/scripts/broadcast-igmp-discovery.nse
+++ b/scripts/broadcast-igmp-discovery.nse
@@ -309,10 +309,12 @@ action = function(host, port)
     local condvar = nmap.condvar(responses)
     -- Wait for the listening threads to finish
     repeat
-	condvar("wait")
 	for thread in pairs(lthreads) do
 	    if coroutine.status(thread) == "dead" then lthreads[thread] = nil end
 	end
+	if ( next(lthreads) ) then
+		condvar("wait")
+	end
     until next(lthreads) == nil;
 
     -- Output useful info from the responses
diff --git a/scripts/broadcast-listener.nse b/scripts/broadcast-listener.nse
index 3f5d68fe2..303bcf660 100644
--- a/scripts/broadcast-listener.nse
+++ b/scripts/broadcast-listener.nse
@@ -265,12 +265,14 @@ action = function()
 	
 	-- wait for all threads to finish sniffing
     repeat
-		condvar "wait"
 		for thread in pairs(threads) do
 			if coroutine.status(thread) == "dead" then
 				threads[thread] = nil
 			end
 		end
+		if ( next(threads) ) then
+			condvar "wait"
+		end
 	until next(threads) == nil
 
 	local out_outer = {}
diff --git a/scripts/broadcast-pc-duo.nse b/scripts/broadcast-pc-duo.nse
index 00017d6b5..c1cd61c64 100644
--- a/scripts/broadcast-pc-duo.nse
+++ b/scripts/broadcast-pc-duo.nse
@@ -113,12 +113,14 @@ action = function()
 
 	-- wait until the probes are all done
 	repeat
-		condvar "wait"
 		for thread in pairs(threads) do
 			if coroutine.status(thread) == "dead" then
 				threads[thread] = nil
 			end
 		end
+		if ( next(threads) ) then
+			condvar "wait"
+		end
 	until next(threads) == nil
     
 	table.sort(responses, function(a,b) return a.name < b.name end)
diff --git a/scripts/broadcast-ping.nse b/scripts/broadcast-ping.nse
index decf8d134..d43072a10 100644
--- a/scripts/broadcast-ping.nse
+++ b/scripts/broadcast-ping.nse
@@ -255,10 +255,12 @@ action = function()
 	end
 
 	repeat
-		condvar "wait"
 		for thread in pairs(threads) do
 			if coroutine.status(thread) == "dead" then threads[thread] = nil end
 		end
+		if ( next(threads) ) then
+			condvar "wait"
+		end
 	until next(threads) == nil
 	
 	-- generate output
diff --git a/scripts/broadcast-wsdd-discover.nse b/scripts/broadcast-wsdd-discover.nse
index 112cc5944..e2f153592 100644
--- a/scripts/broadcast-wsdd-discover.nse
+++ b/scripts/broadcast-wsdd-discover.nse
@@ -86,11 +86,13 @@ action = function()
 	local done
 	-- wait for all threads to finish
 	while( not(done) ) do
-		condvar("wait")
 		done = true
 		for thread in pairs(threads) do
 			if (coroutine.status(thread) ~= "dead") then done = false end
 		end
+		if ( not(done) ) then
+			condvar("wait")
+		end
 	end
 
 	if ( results ) then
diff --git a/scripts/dns-brute.nse b/scripts/dns-brute.nse
index 767098be2..fff11ceed 100644
--- a/scripts/dns-brute.nse
+++ b/scripts/dns-brute.nse
@@ -235,11 +235,13 @@ action = function(host)
 		local done
 		-- wait for all threads to finish
 		while( not(done) ) do
-			condvar("wait")
 			done = true
 			for thread in pairs(threads) do
 				if (coroutine.status(thread) ~= "dead") then done = false end
 			end
+			if ( not(done) ) then
+				condvar("wait")
+			end
 		end
 
 		if(dosrv) then
@@ -257,11 +259,13 @@ action = function(host)
 			local done
 			-- wait for all threads to finish
 			while( not(done) ) do
-				condvar("wait")
 				done = true
 				for thread in pairs(threads) do
 					if (coroutine.status(thread) ~= "dead") then done = false end
 				end
+				if ( not(done) ) then
+					condvar("wait")
+				end
 			end
 		end
 
diff --git a/scripts/dns-ip6-arpa-scan.nse b/scripts/dns-ip6-arpa-scan.nse
index 2f757b899..580c5541a 100644
--- a/scripts/dns-ip6-arpa-scan.nse
+++ b/scripts/dns-ip6-arpa-scan.nse
@@ -80,10 +80,12 @@ action = function()
 		
 		local condvar = nmap.condvar(result)
 		repeat
-			condvar "wait"
 			for t in pairs(threads) do
 				if ( coroutine.status(t) == "dead" ) then threads[t] = nil end
 			end
+			if ( next(threads) ) then
+				condvar "wait"
+			end
 		until( next(threads) == nil )
 			
 		if ( 0 == #result ) then
diff --git a/scripts/dns-srv-enum.nse b/scripts/dns-srv-enum.nse
index e4eaa8282..a1fc7631c 100644
--- a/scripts/dns-srv-enum.nse
+++ b/scripts/dns-srv-enum.nse
@@ -167,10 +167,12 @@ action = function(host)
 	
 	local condvar = nmap.condvar(result)
 	repeat
-		condvar "wait"
 		for t in pairs(threads) do
 			if ( coroutine.status(t) == "dead" ) then threads[t] = nil end
 		end
+		if ( next(threads) ) then
+			condvar "wait"
+		end
 	until( next(threads) == nil )
 	
 	table.sort(result, function(a,b) return a.name < b.name end)
diff --git a/scripts/http-slowloris.nse b/scripts/http-slowloris.nse
index 9d1adaa8e..19ddfb5fb 100644
--- a/scripts/http-slowloris.nse
+++ b/scripts/http-slowloris.nse
@@ -239,7 +239,6 @@ local function worker_scheduler(host, port)
 	while not DOSed and not StopAll do
 		-- keep creating new threads, in case we want to run the attack indefinitely
 		repeat
-			condvar("wait")
 			if StopAll then
 				return
 			end
@@ -252,6 +251,9 @@ local function worker_scheduler(host, port)
 			stdnse.print_debug(SCRIPT_NAME .. " [SCHEDULER]: starting new thread")
 			local co = stdnse.new_thread(do_half_http, host, port, obj)
 			Threads[co] = true
+			if ( next(Threads) ) then
+				condvar("wait")
+			end
 		until next(Threads) == nil;
 	end
 end
diff --git a/scripts/krb5-enum-users.nse b/scripts/krb5-enum-users.nse
index 252f1637e..a44a0f558 100644
--- a/scripts/krb5-enum-users.nse
+++ b/scripts/krb5-enum-users.nse
@@ -389,10 +389,12 @@ action = function( host, port )
 	
 	-- wait for all threads to finish up
 	repeat
-		condvar "wait"
 		for t in pairs(threads) do
 			if ( coroutine.status(t) == "dead" ) then threads[t] = nil end
 		end
+		if ( next(threads) ) then
+			condvar "wait"
+		end
 	until( next(threads) == nil )
 	
 	if ( #result > 0 ) then
diff --git a/scripts/lltd-discovery.nse b/scripts/lltd-discovery.nse
index ad91e6d22..8086d7b6b 100644
--- a/scripts/lltd-discovery.nse
+++ b/scripts/lltd-discovery.nse
@@ -308,10 +308,12 @@ action = function()
 	end
 
 	repeat
-		condvar "wait"
 		for thread in pairs(threads) do
 			if coroutine.status(thread) == "dead" then threads[thread] = nil end
 		end
+		if ( next(threads) ) then
+			condvar "wait"
+		end
 	until next(threads) == nil
 	
 	-- generate output
diff --git a/scripts/rpc-grind.nse b/scripts/rpc-grind.nse
index 28f7e04e9..38506879f 100644
--- a/scripts/rpc-grind.nse
+++ b/scripts/rpc-grind.nse
@@ -237,12 +237,14 @@ action = function(host, port)
 
     local condvar = nmap.condvar(result)
     repeat
-        condvar "wait";
         for thread in pairs(lthreads) do
             if coroutine.status(thread) == "dead" then
                 lthreads[thread] = nil
             end
         end
+        if ( next(lthreads) ) then
+            condvar "wait";
+        end
     until next(lthreads) == nil;
 
     -- Check the result and set the port version.
diff --git a/scripts/rtsp-url-brute.nse b/scripts/rtsp-url-brute.nse
index b8683e70d..876b7d3c9 100644
--- a/scripts/rtsp-url-brute.nse
+++ b/scripts/rtsp-url-brute.nse
@@ -125,10 +125,12 @@ action = function(host, port)
 	end
 
 	repeat
-		condvar "wait"
 		for t in pairs(threads) do
 			if ( coroutine.status(t) == "dead" ) then threads[t] = nil end
 		end
+		if ( next(threads) ) then
+			condvar "wait"
+		end
 	until( next(threads) == nil )
 
 	-- urls that could not be retrieved due to low level errors, such as
diff --git a/scripts/targets-ipv6-multicast-echo.nse b/scripts/targets-ipv6-multicast-echo.nse
index 35e3c244e..e19000641 100644
--- a/scripts/targets-ipv6-multicast-echo.nse
+++ b/scripts/targets-ipv6-multicast-echo.nse
@@ -169,10 +169,12 @@ action = function()
 	end
 
 	repeat
-		condvar "wait"
 		for thread in pairs(threads) do
 			if coroutine.status(thread) == "dead" then threads[thread] = nil end
 		end
+		if ( next(threads) ) then
+			condvar "wait"
+		end
 	until next(threads) == nil
 
 	return format_output(results)
diff --git a/scripts/targets-ipv6-multicast-invalid-dst.nse b/scripts/targets-ipv6-multicast-invalid-dst.nse
index d59de7e49..03af23fb6 100644
--- a/scripts/targets-ipv6-multicast-invalid-dst.nse
+++ b/scripts/targets-ipv6-multicast-invalid-dst.nse
@@ -201,10 +201,12 @@ action = function()
 	end
 
 	repeat
-		condvar "wait"
 		for thread in pairs(threads) do
 			if coroutine.status(thread) == "dead" then threads[thread] = nil end
 		end
+		if ( next(threads) ) then
+			condvar "wait"
+		end
 	until next(threads) == nil
 
 	return format_output(results)
diff --git a/scripts/targets-ipv6-multicast-mld.nse b/scripts/targets-ipv6-multicast-mld.nse
index 2fde34a23..a5d25de9b 100644
--- a/scripts/targets-ipv6-multicast-mld.nse
+++ b/scripts/targets-ipv6-multicast-mld.nse
@@ -166,10 +166,12 @@ action = function()
 	end
 
 	repeat
-		condvar "wait"
 		for thread in pairs(threads) do
 			if coroutine.status(thread) == "dead" then threads[thread] = nil end
 		end
+		if ( next(threads) ) then
+			condvar "wait"
+		end
 	until next(threads) == nil
 
 	return format_output(results)
diff --git a/scripts/targets-ipv6-multicast-slaac.nse b/scripts/targets-ipv6-multicast-slaac.nse
index 0b0a660ed..a1ea20fb7 100644
--- a/scripts/targets-ipv6-multicast-slaac.nse
+++ b/scripts/targets-ipv6-multicast-slaac.nse
@@ -251,10 +251,12 @@ action = function()
 	end
 
 	repeat
-		condvar "wait"
 		for thread in pairs(threads) do
 			if coroutine.status(thread) == "dead" then threads[thread] = nil end
 		end
+		if ( next(threads) ) then
+			condvar "wait"
+		end
 	until next(threads) == nil
 
 	return format_output(results)
diff --git a/scripts/wsdd-discover.nse b/scripts/wsdd-discover.nse
index d749106dd..c656d9314 100644
--- a/scripts/wsdd-discover.nse
+++ b/scripts/wsdd-discover.nse
@@ -75,11 +75,13 @@ action = function(host, port)
 	local done
 	-- wait for all threads to finish
 	while( not(done) ) do
-		condvar("wait")
 		done = true
 		for thread in pairs(threads) do
 			if (coroutine.status(thread) ~= "dead") then done = false end
 		end
+		if ( not(done) ) then
+			condvar("wait")
+		end
 	end
 
 	if ( results ) then