diff --git a/crates/loro-core/examples/test.rs b/crates/loro-core/examples/test.rs
index 553cc52b..8cd9eba6 100644
--- a/crates/loro-core/examples/test.rs
+++ b/crates/loro-core/examples/test.rs
@@ -7,7 +7,7 @@ fn main() {
     use crdt_list::test::Action::*;
     use loro_core::container::text::tracker::yata::YataImpl;
     let mut actions = vec![];
-    for i in 0..10000_usize {
+    for i in 0..500_usize {
         actions.push(if i % 2 == 0 {
             NewOp {
                 client_id: i as u8,
@@ -22,6 +22,9 @@ fn main() {
         })
     }
 
-    test::test_with_actions::<YataImpl>(5, 100, actions);
+    for _ in 0..1000 {
+        test::test_with_actions::<YataImpl>(5, 100, actions.clone());
+    }
+
     println!("HAHA");
 }
diff --git a/crates/loro-core/justfile b/crates/loro-core/justfile
index 164a1fb4..3598ca70 100644
--- a/crates/loro-core/justfile
+++ b/crates/loro-core/justfile
@@ -16,3 +16,9 @@ deny:
 
 crev:
   cargo crev crate check
+
+fuzz:
+  cargo fuzz run yata -- -max_total_time=60
+
+flame:
+  cargo flamegraph --example test --features=fuzzing --root
diff --git a/crates/loro-core/src/container/text/tracker/content_map.rs b/crates/loro-core/src/container/text/tracker/content_map.rs
index 63ec1383..17a7d2b3 100644
--- a/crates/loro-core/src/container/text/tracker/content_map.rs
+++ b/crates/loro-core/src/container/text/tracker/content_map.rs
@@ -5,10 +5,7 @@ use rle::{
     HasLength, RleTree, RleVec,
 };
 
-use crate::{
-    id::{Counter, ID},
-    span::IdSpan,
-};
+use crate::{id::ID, span::IdSpan};
 
 use super::y_span::{StatusChange, YSpan, YSpanTreeTrait};