What version of Bun is running?

1.3.8

What platform is your computer?

x86_64-linux-gnu

What steps can reproduce the bug?

// Create string by concatenation (slow in Bun)
let s = '';
for (let i = 0; i < 100000; i++) s += 'A';

// Process characters with slice() - O(n²) in Bun
let m = new Map();
for (let i = 0; i < 100000; i++) {
let k = s.slice(i, i+1); // O(n) per operation in Bun
m.set(k, 1);
}

What is the expected behavior?

Expected (Node.js behavior): ~0.07s (O(n) linear time)

What do you see instead?

Actual (Bun 1.3.8): ~7.4s (O(n²) quadratic time)
Performance difference: 100x slower

Additional information

bug was discovered while debugging this benchmarks suite: https://kostya.github.io/LangArena/