diff --git a/gleam.toml b/gleam.toml
index cb0eff0..84f699e 100644
--- a/gleam.toml
+++ b/gleam.toml
@@ -18,3 +18,4 @@ gleam_stdlib = ">= 0.44.0 and < 2.0.0"
 [dev-dependencies]
 gleeunit = ">= 1.0.0 and < 2.0.0"
 startest = ">= 0.7.0 and < 1.0.0"
+glychee = ">= 1.1.2 and < 2.0.0"
diff --git a/manifest.toml b/manifest.toml
index 5ea11b7..7914b7f 100644
--- a/manifest.toml
+++ b/manifest.toml
@@ -3,8 +3,10 @@
 
 packages = [
   { name = "argv", version = "1.0.2", build_tools = ["gleam"], requirements = [], otp_app = "argv", source = "hex", outer_checksum = "BA1FF0929525DEBA1CE67256E5ADF77A7CDDFE729E3E3F57A5BDCAA031DED09D" },
+  { name = "benchee", version = "1.4.0", build_tools = ["mix"], requirements = ["deep_merge", "statistex", "table"], otp_app = "benchee", source = "hex", outer_checksum = "299CD10DD8CE51C9EA3DDB74BB150F93D25E968F93E4C1FA31698A8E4FA5D715" },
   { name = "bigben", version = "1.0.1", build_tools = ["gleam"], requirements = ["birl", "gleam_erlang", "gleam_otp", "gleam_stdlib"], otp_app = "bigben", source = "hex", outer_checksum = "190E489610A80D76C48BACC75EB8314BD184FF0220AB0F251ABE760B993B91BB" },
   { name = "birl", version = "1.8.0", build_tools = ["gleam"], requirements = ["gleam_regexp", "gleam_stdlib", "ranger"], otp_app = "birl", source = "hex", outer_checksum = "2AC7BA26F998E3DFADDB657148BD5DDFE966958AD4D6D6957DD0D22E5B56C400" },
+  { name = "deep_merge", version = "1.0.0", build_tools = ["mix"], requirements = [], otp_app = "deep_merge", source = "hex", outer_checksum = "CE708E5F094B9CD4E8F2BE4F00D2F4250C4095BE93F8CD6D018C753894885430" },
   { name = "exception", version = "2.1.0", build_tools = ["gleam"], requirements = ["gleam_stdlib"], otp_app = "exception", source = "hex", outer_checksum = "329D269D5C2A314F7364BD2711372B6F2C58FA6F39981572E5CA68624D291F8C" },
   { name = "filepath", version = "1.1.2", build_tools = ["gleam"], requirements = ["gleam_stdlib"], otp_app = "filepath", source = "hex", outer_checksum = "B06A9AF0BF10E51401D64B98E4B627F1D2E48C154967DA7AF4D0914780A6D40A" },
   { name = "gleam_community_ansi", version = "1.4.3", build_tools = ["gleam"], requirements = ["gleam_community_colour", "gleam_regexp", "gleam_stdlib"], otp_app = "gleam_community_ansi", source = "hex", outer_checksum = "8A62AE9CC6EA65BEA630D95016D6C07E4F9973565FA3D0DE68DC4200D8E0DD27" },
@@ -19,14 +21,17 @@ packages = [
   { name = "gleam_yielder", version = "1.1.0", build_tools = ["gleam"], requirements = ["gleam_stdlib"], otp_app = "gleam_yielder", source = "hex", outer_checksum = "8E4E4ECFA7982859F430C57F549200C7749823C106759F4A19A78AEA6687717A" },
   { name = "gleeunit", version = "1.6.1", build_tools = ["gleam"], requirements = ["gleam_stdlib"], otp_app = "gleeunit", source = "hex", outer_checksum = "FDC68A8C492B1E9B429249062CD9BAC9B5538C6FBF584817205D0998C42E1DAC" },
   { name = "glint", version = "1.2.1", build_tools = ["gleam"], requirements = ["gleam_community_ansi", "gleam_community_colour", "gleam_stdlib", "snag"], otp_app = "glint", source = "hex", outer_checksum = "2214C7CEFDE457CEE62140C3D4899B964E05236DA74E4243DFADF4AF29C382BB" },
+  { name = "glychee", version = "1.1.2", build_tools = ["gleam"], requirements = ["benchee"], otp_app = "glychee", source = "hex", outer_checksum = "41784216C213F223095BB3FC3EDDB60CC537835B2340A868EA3931193F7F3824" },
   { name = "ranger", version = "1.4.0", build_tools = ["gleam"], requirements = ["gleam_stdlib", "gleam_yielder"], otp_app = "ranger", source = "hex", outer_checksum = "C8988E8F8CDBD3E7F4D8F2E663EF76490390899C2B2885A6432E942495B3E854" },
   { name = "simplifile", version = "2.3.0", build_tools = ["gleam"], requirements = ["filepath", "gleam_stdlib"], otp_app = "simplifile", source = "hex", outer_checksum = "0A868DAC6063D9E983477981839810DC2E553285AB4588B87E3E9C96A7FB4CB4" },
   { name = "snag", version = "1.1.0", build_tools = ["gleam"], requirements = ["gleam_stdlib"], otp_app = "snag", source = "hex", outer_checksum = "7E9F06390040EB5FAB392CE642771484136F2EC103A92AE11BA898C8167E6E17" },
   { name = "startest", version = "0.7.0", build_tools = ["gleam"], requirements = ["argv", "bigben", "birl", "exception", "gleam_community_ansi", "gleam_erlang", "gleam_javascript", "gleam_regexp", "gleam_stdlib", "glint", "simplifile", "tom"], otp_app = "startest", source = "hex", outer_checksum = "71B9CB82C4B8779A4BD54C7151DF7D0B0F778D0DDE805B782B44EFA7BA8F50DA" },
+  { name = "statistex", version = "1.1.0", build_tools = ["mix"], requirements = [], otp_app = "statistex", source = "hex", outer_checksum = "F5950EA26AD43246BA2CCE54324AC394A4E7408FDCF98B8E230F503A0CBA9CF5" },
   { name = "tom", version = "2.0.0", build_tools = ["gleam"], requirements = ["gleam_stdlib", "gleam_time"], otp_app = "tom", source = "hex", outer_checksum = "74D0C5A3761F7A7D06994755D4D5AD854122EF8E9F9F76A3E7547606D8C77091" },
 ]
 
 [requirements]
 gleam_stdlib = { version = ">= 0.44.0 and < 2.0.0" }
 gleeunit = { version = ">= 1.0.0 and < 2.0.0" }
+glychee = { version = ">= 1.1.2 and < 2.0.0" }
 startest = { version = ">= 0.7.0 and < 1.0.0" }
diff --git a/src/dllist.gleam b/src/dllist.gleam
index 3430225..9222798 100644
--- a/src/dllist.gleam
+++ b/src/dllist.gleam
@@ -35,22 +35,26 @@ pub fn main() {
 
   // from_list([1, 2, 3, 4]) |> echo
 
-  let l1 = new() |> insert(1)
+  let l1 = new() |> insert(1) |> insert(2)
   l1 |> echo
-  let l1t = take(l1, 5)
-  l1t |> echo
-  let l2 = insert(l1, 2) |> move_left
-  l2 |> echo
-  let l2t = take(l2, 5)
-  l2t |> echo
+  get(l1) |> echo
+  // let l1t = take(l1, 5)
+  // l1t |> echo
+  // let l2 = insert(l1, 2) |> move_left
+  // l2 |> echo
+  // let l2t = take(l2, 5)
+  // l2t |> echo
 
-  let l3 = insert(l2, 3)
-  l3 |> echo
-  to_list(l3) |> echo
+  // let l3 = insert(l2, 3)
+  // l3 |> echo
+  // to_list(l3) |> echo
   // let l3t = take(l3, 7)
   // l3t |> echo
   // let l3t2 = take_rev(l3, 7)
   // l3t2 |> echo
+  // let l1 = new_cyclic() |> echo
+  // let l2 = l1 |> insert(1) |> insert(2) |> insert(3)
+  // to_list(l2) |> echo
 }
 
 pub fn new() -> DLList(a) {
@@ -89,7 +93,12 @@ pub fn insert(list: DLList(a), val: a) -> DLList(a) {
   case is_empty(list) {
     True -> {
       let node = Node(val, new_entry_ref, new_entry_ref)
-      DLList(ref + 1, ref, dict.insert(list.mem, ref, node))
+      update_record(
+        list,
+        Some(ref + 1),
+        Some(ref),
+        Some(dict.insert(list.mem, ref, node)),
+      )
     }
     False -> {
       let assert Ok(curr_node) = get_curr_node(list)
@@ -110,11 +119,11 @@ pub fn insert(list: DLList(a), val: a) -> DLList(a) {
         }
         Error(_) -> new_mem
       }
-
-      DLList(
-        counter: list.counter + 1,
-        current: list.counter,
-        mem: dict.insert(new_mem, ref, Node(val, list.current, next)),
+      update_record(
+        list,
+        Some(list.counter + 1),
+        Some(list.counter),
+        Some(dict.insert(new_mem, ref, Node(val, list.current, next))),
       )
     }
   }
@@ -122,12 +131,23 @@ pub fn insert(list: DLList(a), val: a) -> DLList(a) {
 
 fn update_record(
   list: DLList(a),
-  current: Int,
-  mem: dict.Dict(Int, Node(a)),
+  counter: Option(Int),
+  current: Option(Int),
+  mem: Option(dict.Dict(Int, Node(a))),
 ) -> DLList(a) {
   case list {
-    DLList(_, _, _) -> DLList(..list, current:, mem:)
-    CyclicList(_, _, _) -> CyclicList(..list, current:, mem:)
+    DLList(_, _, _) ->
+      DLList(
+        counter: option.unwrap(counter, list.counter),
+        current: option.unwrap(current, list.current),
+        mem: option.unwrap(mem, list.mem),
+      )
+    CyclicList(_, _, _) ->
+      CyclicList(
+        counter: option.unwrap(counter, list.counter),
+        current: option.unwrap(current, list.current),
+        mem: option.unwrap(mem, list.mem),
+      )
   }
 }
 
@@ -146,44 +166,54 @@ pub fn delete(list: DLList(a)) -> DLList(a) {
         _, 0 -> {
           update_record(
             list,
-            l,
-            update_dict_entry(mem, l, fn(n) { Node(..n, right: r) }),
+            None,
+            Some(l),
+            Some(update_dict_entry(mem, l, fn(n) { Node(..n, right: r) })),
           )
         }
         _, r if r == list.current -> {
           update_record(
             list,
-            l,
-            update_dict_entry(mem, l, fn(n) { Node(..n, right: l) }),
+            None,
+            Some(l),
+            Some(update_dict_entry(mem, l, fn(n) { Node(..n, right: l) })),
           )
         }
         0, _ -> {
           update_record(
             list,
-            r,
-            update_dict_entry(mem, r, fn(n) { Node(..n, left: l) }),
+            None,
+            Some(r),
+            Some(update_dict_entry(mem, r, fn(n) { Node(..n, left: l) })),
           )
         }
         l, _ if l == list.current -> {
           update_record(
             list,
-            r,
-            update_dict_entry(mem, r, fn(n) { Node(..n, left: r) }),
+            None,
+            Some(r),
+            Some(update_dict_entry(mem, r, fn(n) { Node(..n, left: r) })),
           )
         }
         l, r if l == r -> {
           update_record(
             list,
-            r,
-            update_dict_entry(mem, r, fn(n) { Node(..n, left: r, right: r) }),
+            None,
+            Some(r),
+            Some(
+              update_dict_entry(mem, r, fn(n) { Node(..n, left: r, right: r) }),
+            ),
           )
         }
         _, _ -> {
           update_record(
             list,
-            r,
-            update_dict_entry(mem, r, fn(n) { Node(..n, left: l) })
+            None,
+            Some(r),
+            Some(
+              update_dict_entry(mem, r, fn(n) { Node(..n, left: l) })
               |> update_dict_entry(l, fn(n) { Node(..n, right: r) }),
+            ),
           )
         }
       }
@@ -199,10 +229,9 @@ fn do_move_right(list: DLList(a)) -> Result(DLList(a), Nil) {
   case get_curr_node(list) {
     Error(_) -> Error(Nil)
     Ok(node) -> {
-      case node.right, list {
-        0, _ -> Error(Nil)
-        r, DLList(_, _, _) -> Ok(DLList(..list, current: r))
-        r, CyclicList(_, _, _) -> Ok(CyclicList(..list, current: r))
+      case node.right {
+        0 -> Error(Nil)
+        r -> Ok(update_record(list, None, Some(r), None))
       }
     }
   }
@@ -217,10 +246,9 @@ fn do_move_left(list: DLList(a)) -> Result(DLList(a), Nil) {
   case get_curr_node(list) {
     Error(_) -> Error(Nil)
     Ok(node) -> {
-      case node.left, list {
-        0, _ -> Error(Nil)
-        l, DLList(_, _, _) -> Ok(DLList(..list, current: l))
-        l, CyclicList(_, _, _) -> Ok(CyclicList(..list, current: l))
+      case node.left {
+        0 -> Error(Nil)
+        l -> Ok(update_record(list, None, Some(l), None))
       }
     }
   }
@@ -230,6 +258,10 @@ pub fn from_list(list: List(a)) -> DLList(a) {
   list.fold(list, new(), insert)
 }
 
+pub fn from_list_cyclic(list: List(a)) -> DLList(a) {
+  list.fold(list, new_cyclic(), insert)
+}
+
 pub fn take(list: DLList(a), n_times: Int) -> List(a) {
   take_loop(list, n_times, [])
 }
@@ -280,7 +312,7 @@ pub fn to_list(list: DLList(a)) -> List(a) {
     DLList(_, _, _) -> DLList(..list, current: 1)
     CyclicList(_, _, _) -> list
   }
-  to_list_loop(Ok(list), list.current, [])
+  to_list_loop(Ok(list), list.current, []) |> list.reverse
 }
 
 fn to_list_loop(
@@ -288,43 +320,35 @@ fn to_list_loop(
   start_ref: Int,
   acc: List(a),
 ) -> List(a) {
-  case list {
-    Error(_) -> list.reverse(acc)
-    Ok(list) -> {
+  case list |> echo {
+    Error(_) -> acc
+    Ok(DLList(_, _, _) as list) -> {
       case get(list) {
         Error(_) -> []
         Ok(val) -> to_list_loop(do_move_right(list), start_ref, [val, ..acc])
       }
     }
+    Ok(CyclicList(_, _, _) as list) -> {
+      case get(list) {
+        Error(_) -> []
+        Ok(_) if start_ref == list.current && acc != [] -> acc
+        Ok(val) -> to_list_loop(do_move_right(list), start_ref, [val, ..acc])
+      }
+    }
   }
 }
 
 pub fn update(list: DLList(a), value: a) -> Result(DLList(a), Nil) {
   use <- bool.guard(when: is_empty(list), return: Error(Nil))
-  case get_curr_node(list), list {
-    Error(_), _ -> Error(Nil)
-    Ok(curr_node), DLList(_, _, _) ->
-      Ok(
-        DLList(
-          ..list,
-          mem: dict.insert(
-            list.mem,
-            list.current,
-            Node(..curr_node, val: value),
-          ),
-        ),
-      )
-    Ok(curr_node), CyclicList(_, _, _) ->
-      Ok(
-        CyclicList(
-          ..list,
-          mem: dict.insert(
-            list.mem,
-            list.current,
-            Node(..curr_node, val: value),
-          ),
-        ),
-      )
+  case get_curr_node(list) {
+    Error(_) -> Error(Nil)
+    Ok(curr_node) ->
+      Ok(update_record(
+        list,
+        None,
+        None,
+        Some(dict.insert(list.mem, list.current, Node(..curr_node, val: value))),
+      ))
   }
 }
 
diff --git a/test/benchmark.gleam b/test/benchmark.gleam
new file mode 100644
index 0000000..752384e
--- /dev/null
+++ b/test/benchmark.gleam
@@ -0,0 +1,113 @@
+import dllist
+import gleam/list
+import glychee/benchmark
+import glychee/configuration
+
+@target(erlang)
+pub fn main() {
+  configuration.initialize()
+  configuration.set_pair(configuration.Warmup, 2)
+  configuration.set_pair(configuration.Parallel, 2)
+
+  benchmark2()
+}
+
+@target(erlang)
+fn benchmark() {
+  benchmark.run(
+    [
+      benchmark.Function(
+        label: "list append",
+        callable: fn(data: #(List(Int), Int)) {
+          fn() {
+            list.fold(data.0, [], fn(acc, i) { [i, ..acc] })
+            |> list.reverse
+            |> insert_at(data.1, 999)
+            Nil
+          }
+        },
+      ),
+      benchmark.Function(
+        label: "dllist insert",
+        callable: fn(data: #(List(Int), Int)) {
+          fn() {
+            list.fold(data.0, dllist.new(), fn(acc, i) { dllist.insert(acc, i) })
+            |> move_left_n(data.1)
+            |> dllist.insert(999)
+            Nil
+          }
+        },
+      ),
+    ],
+    [
+      benchmark.Data(label: "6 Items", data: #(list.range(1, 6), 3)),
+      benchmark.Data(label: "10 Items", data: #(list.range(1, 10), 5)),
+      benchmark.Data(label: "100 Items", data: #(list.range(1, 100), 50)),
+    ],
+  )
+}
+
+@target(erlang)
+fn benchmark2() {
+  benchmark.run(
+    [
+      benchmark.Function(
+        label: "list append",
+        callable: fn(data: #(List(Int), dllist.DLList(Int), Int)) {
+          fn() {
+            let _ = insert_at(data.0, data.2, 999)
+            Nil
+          }
+        },
+      ),
+      benchmark.Function(
+        label: "dllist insert",
+        callable: fn(data: #(List(Int), dllist.DLList(Int), Int)) {
+          fn() {
+            let _ = dllist.insert(data.1, 999)
+            Nil
+          }
+        },
+      ),
+    ],
+    [
+      benchmark.Data(label: "6 Items", data: #(
+        list.range(1, 6),
+        dllist.from_list(list.range(1, 6)) |> move_left_n(3),
+        3,
+      )),
+      benchmark.Data(label: "10 Items", data: #(
+        list.range(1, 10),
+        dllist.from_list(list.range(1, 10)) |> move_left_n(5),
+        5,
+      )),
+      benchmark.Data(label: "100 Items", data: #(
+        list.range(1, 100),
+        dllist.from_list(list.range(1, 100)) |> move_left_n(50),
+        50,
+      )),
+      benchmark.Data(label: "1000 Items", data: #(
+        list.range(1, 1000),
+        dllist.from_list(list.range(1, 1000)) |> move_left_n(500),
+        500,
+      )),
+      benchmark.Data(label: "10000 Items", data: #(
+        list.range(1, 10_000),
+        dllist.from_list(list.range(1, 10_000)) |> move_left_n(5000),
+        5000,
+      )),
+    ],
+  )
+}
+
+fn insert_at(list: List(a), pos: Int, value: a) -> List(a) {
+  let #(l1, l2) = list.split(list, pos)
+  list.append(l1, [value, ..l2])
+}
+
+fn move_left_n(list: dllist.DLList(a), n: Int) -> dllist.DLList(a) {
+  case n {
+    0 -> list
+    n -> move_left_n(dllist.move_left(list), n - 1)
+  }
+}
diff --git a/test/dllist_test.gleam b/test/dllist_test.gleam
index 1ea2439..945504b 100644
--- a/test/dllist_test.gleam
+++ b/test/dllist_test.gleam
@@ -1,10 +1,22 @@
 import dllist
+import gleam/dict
 import startest
 
 pub fn main() -> Nil {
   startest.run(startest.default_config())
 }
 
+pub fn new_tests() {
+  startest.describe("new instance", [
+    startest.it("terminated list", fn() {
+      assert dllist.new() == dllist.DLList(1, 0, dict.from_list([]))
+    }),
+    startest.it("cyclic list", fn() {
+      assert dllist.new_cyclic() == dllist.CyclicList(1, 0, dict.from_list([]))
+    }),
+  ])
+}
+
 pub fn is_empty_tests() {
   startest.describe("is_emtpy", [
     startest.it("terminated list", fn() {
@@ -19,3 +31,31 @@ pub fn is_empty_tests() {
     }),
   ])
 }
+
+pub fn from_list_tests() {
+  startest.describe("from_list", [
+    startest.it("terminated list", fn() {
+      assert dllist.is_empty(dllist.from_list([]))
+
+      assert !dllist.is_empty(dllist.from_list([1]))
+
+      assert dllist.from_list([1]) |> dllist.get == Ok(1)
+      assert dllist.from_list([1, 2, 3, 4]) |> dllist.get == Ok(4)
+
+      assert dllist.from_list([1]) |> dllist.to_list == [1]
+      assert dllist.from_list([1, 2, 3, 4]) |> dllist.to_list == [1, 2, 3, 4]
+    }),
+    startest.it("cyclic list", fn() {
+      assert dllist.is_empty(dllist.from_list_cyclic([]))
+
+      assert !dllist.is_empty(dllist.from_list_cyclic([1]))
+
+      assert dllist.from_list_cyclic([1]) |> dllist.get == Ok(1)
+      assert dllist.from_list_cyclic([1, 2, 3, 4]) |> dllist.get == Ok(4)
+
+      assert dllist.from_list_cyclic([1]) |> dllist.to_list == [1]
+      assert dllist.from_list_cyclic([1, 2, 3, 4]) |> dllist.to_list
+        == [4, 1, 2, 3]
+    }),
+  ])
+}