diff --git a/.gitignore b/.gitignore
index 599be4e..b01f73b 100644
--- a/.gitignore
+++ b/.gitignore
@@ -2,3 +2,5 @@
 *.ez
 /build
 erl_crash.dump
+/node_modules
+/build_*
diff --git a/bench/fstw.mjs b/bench/fstw.mjs
new file mode 100644
index 0000000..b01ba46
--- /dev/null
+++ b/bench/fstw.mjs
@@ -0,0 +1,8 @@
+import _string_width from './node_modules/fast-string-truncated-width/dist/index.js'
+const string_width = (input) => _string_width(input, {limit:Infinity, ellipsis:""}).width
+
+let sum = 0;
+for(let i = 0; i < 10000; ++i) {
+  sum += string_width("\x1b[1;95m· \x1b[0m\x1b[K\x1b[33mdeno\x1b[0m\x1b[K, \x1b[33mtypescript\x1b[0m\x1b[K, \x1b[33mts\x1b[0m\x1b[K")
+}
+console.log(sum)
diff --git a/bench/sw.mjs b/bench/sw.mjs
new file mode 100644
index 0000000..de3a454
--- /dev/null
+++ b/bench/sw.mjs
@@ -0,0 +1,8 @@
+import { line as string_width } from './build/dev/javascript/string_width/string_width.mjs'
+import { toList } from './build/dev/javascript/string_width/gleam.mjs'
+
+let sum = 0;
+for(let i = 0; i < 10000; ++i) {
+  sum += string_width("\x1b[1;95m· \x1b[0m\x1b[K\x1b[33mdeno\x1b[0m\x1b[K, \x1b[33mtypescript\x1b[0m\x1b[K, \x1b[33mts\x1b[0m\x1b[K", toList([]))
+}
+console.log(sum)
diff --git a/package-lock.json b/package-lock.json
new file mode 100644
index 0000000..f7cb58e
--- /dev/null
+++ b/package-lock.json
@@ -0,0 +1,17 @@
+{
+  "name": "string-width",
+  "lockfileVersion": 3,
+  "requires": true,
+  "packages": {
+    "": {
+      "dependencies": {
+        "fast-string-truncated-width": "^1.1.0"
+      }
+    },
+    "node_modules/fast-string-truncated-width": {
+      "version": "1.1.0",
+      "resolved": "https://registry.npmjs.org/fast-string-truncated-width/-/fast-string-truncated-width-1.1.0.tgz",
+      "integrity": "sha512-FfsFREOllHpnSl6cxpLi6wvqd9UebrZPxWlOJCCcWoOJzy02xyjPbafF9tyg2Usnf3GLmRr5Q6s7n+GO+6VB5A=="
+    }
+  }
+}
diff --git a/package.json b/package.json
new file mode 100644
index 0000000..702e7eb
--- /dev/null
+++ b/package.json
@@ -0,0 +1,5 @@
+{
+  "dependencies": {
+    "fast-string-truncated-width": "^1.1.0"
+  }
+}
diff --git a/src/string_width.gleam b/src/string_width.gleam
index 3dc1e23..6d702ce 100644
--- a/src/string_width.gleam
+++ b/src/string_width.gleam
@@ -1,4 +1,3 @@
-import gleam/bit_array
 import gleam/int
 import gleam/list
 import gleam/regex
@@ -237,26 +236,20 @@ fn is_wide(cp: Int) -> Bool {
   }
 }
 
+@external(javascript, "./string_width_ffi.mjs", "table_lookup")
 fn table_lookup(table: BitArray, value: Int) -> Bool {
   let hi = int.bitwise_shift_right(value, 8)
   let md = int.bitwise_shift_right(int.bitwise_and(value, 0xff), 3)
   let lo = int.bitwise_and(value, 7)
 
-  int.bitwise_shift_right(at(table, at(table, hi) * 32 + md), lo) % 2 != 0
-}
+  let lvl1_skip = hi * 8
+  let assert <<_:size(lvl1_skip), lvl1:int, _:bits>> = table
 
-fn at(bits: BitArray, at position: Int) -> Int {
-  // NOTE: This bit array size option is in patterns is not supported for JavaScript compilation.
-  // let bit_index = position * 8
-  // case bits {
-  //   <<_:size(bit_index), x:int, _:bits>> -> x
-  //   _ -> panic
-  // }
+  let lvl2_skip = { lvl1 * 32 + md } * 8
+  let assert <<_:size(lvl2_skip), lvl3:int, _:bits>> = table
 
-  case bit_array.slice(bits, at: position, take: 1) {
-    Ok(<<x>>) -> x
-    _ -> panic
-  }
+  // TODO: worth collapsing into a single skip?
+  int.bitwise_shift_right(lvl3, lo) % 2 != 0
 }
 
 const nonspacing = <<
diff --git a/src/string_width_ffi.mjs b/src/string_width_ffi.mjs
new file mode 100644
index 0000000..e32acda
--- /dev/null
+++ b/src/string_width_ffi.mjs
@@ -0,0 +1,11 @@
+export function table_lookup(table, value) {
+  let hi = value >> 8; // $int.bitwise_shift_right(value, 8);
+  let md = (value & 0xff) >> 3; // $int.bitwise_shift_right($int.bitwise_and(value, 0xff), 3);
+  let lo = value & 7; // $int.bitwise_and(value, 7);
+  // return (remainderInt(
+  //   $int.bitwise_shift_right(at(table, at(table, hi) * 32 + md), lo),
+  //   2
+  // )) !== 0;
+  return ((table.byteAt(table.byteAt(hi) * 32 + md) >> lo) & 1) > 0;
+}
+