perf(router): iterate routes with for loop (#11111)

for loop has better performance than function ipairs(), especially for huge table.

kong/router/atc.lua

@@ -181,7 +181,9 @@ local function new_from_scratch(routes, get_exp_and_priority)
 
   local new_updated_at = 0
 
-  for _, r in ipairs(routes) do
+  for i = 1, routes_n do
+    local r = routes[i]
+
     local route = r.route
     local route_id = route.id
 
@@ -240,7 +242,9 @@ local function new_from_previous(routes, get_exp_and_priority, old_router)
   local new_updated_at = 0
 
   -- create or update routes
-  for _, r in ipairs(routes) do
+  for i = 1, #routes do
+    local r = routes[i]
+
     local route = r.route
     local route_id = route.id
 

kong/router/utils.lua

@@ -292,8 +292,8 @@ do
     local v0              = 0
     local v1              = 0
 
-    for _, route in ipairs(routes) do
-      local r = route.route
+    for i = 1, #routes do
+      local r = routes[i].route
 
       local paths_t     = r.paths or empty_table
       local headers_t   = r.headers or empty_table