--- a/crates/jrsonnet-evaluator/src/stdlib/manifest.rs
+++ b/crates/jrsonnet-evaluator/src/stdlib/manifest.rs
@@ -259,24 +259,90 @@
 	buf
 }
 
-fn escape_string_json_buf(s: &str, buf: &mut String) {
-	buf.push('"');
-	for c in s.chars() {
-		match c {
-			'"' => buf.push_str("\\\""),
-			'\\' => buf.push_str("\\\\"),
-			'\u{0008}' => buf.push_str("\\b"),
-			'\u{000c}' => buf.push_str("\\f"),
-			'\n' => buf.push_str("\\n"),
-			'\r' => buf.push_str("\\r"),
-			'\t' => buf.push_str("\\t"),
-			c if c < 32 as char || (c >= 127 as char && c <= 159 as char) => {
-				write!(buf, "\\u{:04x}", c as u32).unwrap();
+// Json string encoding was borrowed from https://github.com/serde-rs/json
+
+const BB: u8 = b'b'; // \x08
+const TT: u8 = b't'; // \x09
+const NN: u8 = b'n'; // \x0A
+const FF: u8 = b'f'; // \x0C
+const RR: u8 = b'r'; // \x0D
+const QU: u8 = b'"'; // \x22
+const BS: u8 = b'\\'; // \x5C
+const UU: u8 = b'u'; // \x00...\x1F except the ones above
+const __: u8 = 0;
+
+// Lookup table of escape sequences. A value of b'x' at index i means that byte
+// i is escaped as "\x" in JSON. A value of 0 means that byte i is not escaped.
+static ESCAPE: [u8; 256] = [
+	//   1   2   3   4   5   6   7   8   9   A   B   C   D   E   F
+	UU, UU, UU, UU, UU, UU, UU, UU, BB, TT, NN, UU, FF, RR, UU, UU, // 0
+	UU, UU, UU, UU, UU, UU, UU, UU, UU, UU, UU, UU, UU, UU, UU, UU, // 1
+	__, __, QU, __, __, __, __, __, __, __, __, __, __, __, __, __, // 2
+	__, __, __, __, __, __, __, __, __, __, __, __, __, __, __, __, // 3
+	__, __, __, __, __, __, __, __, __, __, __, __, __, __, __, __, // 4
+	__, __, __, __, __, __, __, __, __, __, __, __, BS, __, __, __, // 5
+	__, __, __, __, __, __, __, __, __, __, __, __, __, __, __, __, // 6
+	__, __, __, __, __, __, __, __, __, __, __, __, __, __, __, __, // 7
+	__, __, __, __, __, __, __, __, __, __, __, __, __, __, __, __, // 8
+	__, __, __, __, __, __, __, __, __, __, __, __, __, __, __, __, // 9
+	__, __, __, __, __, __, __, __, __, __, __, __, __, __, __, __, // A
+	__, __, __, __, __, __, __, __, __, __, __, __, __, __, __, __, // B
+	__, __, __, __, __, __, __, __, __, __, __, __, __, __, __, __, // C
+	__, __, __, __, __, __, __, __, __, __, __, __, __, __, __, __, // D
+	__, __, __, __, __, __, __, __, __, __, __, __, __, __, __, __, // E
+	__, __, __, __, __, __, __, __, __, __, __, __, __, __, __, __, // F
+];
+
+fn escape_string_json_buf(value: &str, buf: &mut String) {
+	// Safety: we only write correct utf-8 in this function
+	let mut buf: &mut Vec<u8> = unsafe { core::mem::transmute(buf) };
+	let bytes = value.as_bytes();
+
+	// Perfect for ascii strings, removes any reallocations
+	buf.reserve(value.len() + 2);
+
+	buf.push(b'"');
+
+	let mut start = 0;
+
+	for (i, &byte) in bytes.iter().enumerate() {
+		let escape = ESCAPE[byte as usize];
+		if escape == __ {
+			continue;
+		}
+
+		if start < i {
+			buf.extend_from_slice(&bytes[start..i]);
+		}
+		start = i + 1;
+
+		match escape {
+			self::BB | self::TT | self::NN | self::FF | self::RR | self::QU | self::BS => {
+				buf.extend_from_slice(&[b'\\', escape])
+			}
+			self::UU => {
+				static HEX_DIGITS: [u8; 16] = *b"0123456789abcdef";
+				let bytes = &[
+					b'\\',
+					b'u',
+					b'0',
+					b'0',
+					HEX_DIGITS[(byte >> 4) as usize],
+					HEX_DIGITS[(byte & 0xF) as usize],
+				];
+				buf.extend_from_slice(bytes)
 			}
-			c => buf.push(c),
+			_ => unreachable!(),
 		}
 	}
-	buf.push('"');
+
+	if start == bytes.len() {
+		buf.push(b'"');
+		return;
+	}
+
+	buf.extend_from_slice(&bytes[start..]);
+	buf.push(b'"');
 }
 
 pub struct YamlFormat<'s> {