diff --git a/src/LuaScripts.php b/src/LuaScripts.php
index ef260f03..dc4b37a7 100644
--- a/src/LuaScripts.php
+++ b/src/LuaScripts.php
@@ -21,16 +21,18 @@ public static function updateMetrics()
             redis.call('sadd', KEYS[2], KEYS[1])
             
             local hash = redis.call('hmget', KEYS[1], 'throughput', 'runtime')
-
-            local throughput = hash[1] + 1
+            
+            local throughput = tonumber(hash[1]) or 0
+            
+            throughput = throughput + 1
+            
             local runtime = 0
-
             if hash[2] then
-                runtime = ((hash[1] * tonumber(hash[2])) + tonumber(ARGV[1])) / throughput
+                runtime = ((tonumber(hash[1]) * tonumber(hash[2])) + tonumber(ARGV[1])) / throughput
             else
                 runtime = tonumber(ARGV[1])
             end
-
+            
             redis.call('hmset', KEYS[1], 'throughput', throughput, 'runtime', runtime)
 LUA;
     }
@@ -50,29 +52,26 @@ public static function purge()
         return <<<'LUA'
             
             local count = 0
-            local cursor = 0
+            local batch_size = tonumber(100)
+            local start = tonumber(0)
             
-            repeat
-                -- Iterate over the recent jobs sorted set
-                local scanner = redis.call('zscan', KEYS[1], cursor)
-                cursor = scanner[1]
-
-                for i = 1, #scanner[2], 2 do
-                    local jobid = scanner[2][i]
-                    local hashkey = ARGV[1] .. jobid
-                    local job = redis.call('hmget', hashkey, 'status', 'queue')
-
-                    -- Delete the pending/reserved jobs, that match the queue
-                    -- name, from the sorted sets as well as the job hash
-                    if((job[1] == 'reserved' or job[1] == 'pending') and job[2] == ARGV[2]) then
-                        redis.call('zrem', KEYS[1], jobid)
-                        redis.call('zrem', KEYS[2], jobid)
-                        redis.call('del', hashkey)
-                        count = count + 1
-                    end           
+            -- Use ZRANGE to get a range of elements from the sorted set in a deterministic way
+            local jobs = redis.call('zrange', KEYS[1], start, start + batch_size - 1)
+            
+            for i = 1, #jobs do
+                local jobid = jobs[i]
+                local hashkey = ARGV[1] .. jobid
+                local job = redis.call('hmget', hashkey, 'status', 'queue')
+            
+                -- Delete the pending/reserved jobs that match the queue name
+                if ((job[1] == 'reserved' or job[1] == 'pending') and job[2] == ARGV[2]) then
+                    redis.call('zrem', KEYS[1], jobid)
+                    redis.call('zrem', KEYS[2], jobid)
+                    redis.call('del', hashkey)
+                    count = count + 1
                 end
-            until cursor == '0'
-
+            end
+            
             return count
 LUA;
     }