make it about three times faster

Cargo.toml

@@ -5,3 +5,6 @@ edition = "2024"
 
 [dependencies]
 rand = { version = "0.9.0", features = ["small_rng", "std_rng"] }
+
+[profile.release]
+lto = "fat"

src/main.rs

@@ -1,16 +1,24 @@
-use std::io::{self, BufWriter, Write};
+use std::io::{self, Write};
 
-use rand::{distr::StandardUniform, rngs::SmallRng, Rng, SeedableRng};
+use rand::{Rng, SeedableRng, rngs::SmallRng};
+
+const BUFFER_SIZE: usize = 8192;
+const BITS_PER_SAMPLE: usize = u64::BITS as usize;
 
 fn main() {
-    let mut stdout = BufWriter::new(io::stdout().lock());
-    let rng = SmallRng::from_os_rng();
+    let mut stdout = io::stdout().lock();
+    let mut rng = SmallRng::from_os_rng();
 
-    for bits in rng.sample_iter::<u64, _>(StandardUniform) {
-        for i in 0..64 {
-            let bit = (bits >> i) & 1;
-            let c = if bit == 0 { b'/' } else { b'\\' };
-            let _ = stdout.write_all(&[c]);
+    let mut buf_out = [b'A'; BUFFER_SIZE];
+    loop {
+        for chunk_idx in 0..(BUFFER_SIZE / BITS_PER_SAMPLE) {
+            let bits: u64 = rng.random();
+            for bit_idx in 0..BITS_PER_SAMPLE {
+                let bit = (bits >> bit_idx) & 1;
+                let c = if bit == 0 { b'\\' } else { b'/' };
+                buf_out[chunk_idx * BITS_PER_SAMPLE + bit_idx] = c;
+            }
         }
+        let _ = stdout.write_all(&buf_out);
     }
 }