diff --git a/Cargo.lock b/Cargo.lock
index ffaa43e..02b8812 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -20,6 +20,7 @@ dependencies = [
  "difference",
  "divan",
  "glob",
+ "memchr",
  "serde",
  "snapbox",
  "toml",
@@ -393,9 +394,9 @@ checksum = "90ed8c1e510134f979dbc4f070f87d4313098b704861a105fe34231c70a3901c"
 
 [[package]]
 name = "memchr"
-version = "2.7.2"
+version = "2.7.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "6c8640c5d730cb13ebd907d8d04b52f55ac9a2eec55b440c8892f40d56c76c1d"
+checksum = "78ca9ab1a0babb1e7d5695e3530886289c18cf2f87ec19a575a0abdce112e3a3"
 
 [[package]]
 name = "normalize-line-endings"
diff --git a/Cargo.toml b/Cargo.toml
index 2b72bd9..d59fa9f 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -25,6 +25,7 @@ maintenance = { status = "actively-developed" }
 
 [dependencies]
 anstyle = "1.0.4"
+memchr = { version = "2.7.4", optional = true }
 unicode-width = "0.1.11"
 
 [dev-dependencies]
@@ -47,6 +48,7 @@ harness = false
 
 [features]
 default = []
+simd = ["memchr"]
 testing-colors = []
 
 [lints.rust]
diff --git a/src/renderer/display_list.rs b/src/renderer/display_list.rs
index d94a660..b5fef26 100644
--- a/src/renderer/display_list.rs
+++ b/src/renderer/display_list.rs
@@ -893,7 +893,7 @@ fn fold_prefix_suffix(mut snippet: snippet::Snippet<'_>) -> snippet::Snippet<'_>
     if let Some(before_new_start) = snippet.source[0..ann_start].rfind('\n') {
         let new_start = before_new_start + 1;
 
-        let line_offset = snippet.source[..new_start].lines().count();
+        let line_offset = newline_count(&snippet.source[..new_start]);
         snippet.line_start += line_offset;
 
         snippet.source = &snippet.source[new_start..];
@@ -919,6 +919,17 @@ fn fold_prefix_suffix(mut snippet: snippet::Snippet<'_>) -> snippet::Snippet<'_>
     snippet
 }
 
+fn newline_count(body: &str) -> usize {
+    #[cfg(feature = "simd")]
+    {
+        memchr::memchr_iter(b'\n', body.as_bytes()).count()
+    }
+    #[cfg(not(feature = "simd"))]
+    {
+        body.lines().count()
+    }
+}
+
 fn fold_body(body: Vec<DisplayLine<'_>>) -> Vec<DisplayLine<'_>> {
     const INNER_CONTEXT: usize = 1;
     const INNER_UNFOLD_SIZE: usize = INNER_CONTEXT * 2 + 1;