diff --git a/CHANGELOG.md b/CHANGELOG.md
index 01f754f2..c3a28d34 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -6,6 +6,9 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+### Changed
+- metrics registry refactoring to search with `O(1)` [#188](https://github.com/tarantool/metrics/issues/188)
+
 ### Fixed
 - be gentle to http routes, don't leave gaps in the array
   [#246](https://github.com/tarantool/metrics/issues/246)
diff --git a/metrics/registry.lua b/metrics/registry.lua
index 1e995163..8dc4bda2 100644
--- a/metrics/registry.lua
+++ b/metrics/registry.lua
@@ -15,11 +15,7 @@ function Registry:clear()
 end
 
 function Registry:find(kind, name)
-    for _, c in ipairs(self.collectors) do
-        if c.name == name and c.kind == kind then
-            return c
-        end
-    end
+    return self.collectors[name .. kind]
 end
 
 function Registry:find_or_create(class, name, ...)
@@ -32,22 +28,18 @@ end
 
 function Registry:register(collector)
     assert(collector ~= nil, 'Collector is empty')
-    assert(not is_empty(collector.name), "Collector''s name is empty")
-    assert(not is_empty(collector.kind), "Collector''s kind is empty")
+    assert(not is_empty(collector.name), "Collector's name is empty")
+    assert(not is_empty(collector.kind), "Collector's kind is empty")
     if self:find(collector.kind, collector.name) then
         error('Already registered')
     end
     collector:set_registry(self)
-    table.insert(self.collectors, collector)
+    self.collectors[collector.name .. collector.kind] = collector
     return collector
 end
 
 function Registry:unregister(collector)
-    for i, c in ipairs(self.collectors) do
-        if c.name == collector.name and c.kind == collector.kind then
-            table.remove(self.collectors, i)
-        end
-    end
+    self.collectors[collector.name .. collector.kind] = nil
 end
 
 function Registry:invoke_callbacks()
diff --git a/test/collectors_test.lua b/test/collectors_test.lua
index 16eadf62..62c683ba 100755
--- a/test/collectors_test.lua
+++ b/test/collectors_test.lua
@@ -21,6 +21,14 @@ g.after_each(function()
     metrics.clear()
 end)
 
+local function len(tbl)
+    local l = 0
+    for _ in pairs(tbl) do
+        l = l + 1
+    end
+    return l
+end
+
 g.test_counter = function()
     t.assert_error_msg_contains("bad argument #1 to counter (string expected, got nil)", function()
         metrics.counter()
@@ -38,7 +46,7 @@ g.test_counter = function()
     local collectors = metrics.collectors()
     local observations = metrics.collect()
     local obs = utils.find_obs('cnt', {}, observations)
-    t.assert_equals(#collectors, 1, 'counter seen as only collector')
+    t.assert_equals(len(collectors), 1, 'counter seen as only collector')
     t.assert_equals(obs.value, 8, '3 + 5 = 8 (via metrics.collectors())')
 
     t.assert_equals(c:collect()[1].value, 8, '3 + 5 = 8')
@@ -70,7 +78,7 @@ g.test_gauge = function()
     local collectors = metrics.collectors()
     local observations = metrics.collect()
     local obs = utils.find_obs('gauge', {}, observations)
-    t.assert_equals(#collectors, 1, 'gauge seen as only collector')
+    t.assert_equals(len(collectors), 1, 'gauge seen as only collector')
     t.assert_equals(obs.value, -2, '3 - 5 = -2 (via metrics.collectors())')
 
     t.assert_equals(gauge:collect()[1].value, -2, '3 - 5 = -2')
@@ -100,7 +108,7 @@ g.test_histogram = function()
     h:observe(5)
 
     local collectors = metrics.collectors()
-    t.assert_equals(#collectors, 1, 'histogram seen as only 1 collector')
+    t.assert_equals(len(collectors), 1, 'histogram seen as only 1 collector')
     local observations = metrics.collect()
     local obs_sum = utils.find_obs('hist_sum', {}, observations)
     local obs_count = utils.find_obs('hist_count', {}, observations)
@@ -117,7 +125,7 @@ g.test_histogram = function()
     h:observe(3, { foo = 'bar' })
 
     collectors = metrics.collectors()
-    t.assert_equals(#collectors, 1, 'still histogram seen as only 1 collector')
+    t.assert_equals(len(collectors), 1, 'still histogram seen as only 1 collector')
     observations = metrics.collect()
     obs_sum = utils.find_obs('hist_sum', { foo = 'bar' }, observations)
     obs_count = utils.find_obs('hist_count', { foo = 'bar' }, observations)
@@ -145,7 +153,7 @@ g.test_counter_cache = function()
     local collectors = metrics.collectors()
     local observations = metrics.collect()
     local obs = utils.find_obs('cnt', {}, observations)
-    t.assert_equals(#collectors, 2, 'counter_1 and counter_2 refer to the same object')
+    t.assert_equals(len(collectors), 2, 'counter_1 and counter_2 refer to the same object')
     t.assert_equals(obs.value, 8, '3 + 5 = 8')
     obs = utils.find_obs('cnt2', {}, observations)
     t.assert_equals(obs.value, 7, 'counter_3 is the only reference to cnt2')
diff --git a/test/lj_metrics_test.lua b/test/lj_metrics_test.lua
index 9582bbbd..c9f1d727 100755
--- a/test/lj_metrics_test.lua
+++ b/test/lj_metrics_test.lua
@@ -50,5 +50,5 @@ g.test_lj_metrics = function()
         "lj_gc_steps_pause",
     }
 
-    t.assert_covers(lj_metrics, expected_lj_metrics)
+    t.assert_items_equals(lj_metrics, expected_lj_metrics)
 end
diff --git a/test/plugins/graphite_test.lua b/test/plugins/graphite_test.lua
index 21242f17..0b152517 100755
--- a/test/plugins/graphite_test.lua
+++ b/test/plugins/graphite_test.lua
@@ -33,6 +33,10 @@ g.before_all(function()
     metrics.enable_default_metrics();
 end)
 
+g.before_each(function()
+    metrics.clear()
+end)
+
 g.after_each(function()
     -- Delete all collectors and global labels
     metrics.clear()
@@ -96,6 +100,7 @@ g.test_graphite_sends_data_to_socket = function()
     local obs_table = graphite_obs:split(' ')
     t.assert_equals(obs_table[1], 'tarantool.test_cnt')
     t.assert_equals(obs_table[2], '1')
+    sock:close()
 end
 
 local function mock_graphite_worker()