diff --git a/bio-io/src/lib.rs b/bio-io/src/lib.rs
index 12c6b2b1..4f08f039 100644
--- a/bio-io/src/lib.rs
+++ b/bio-io/src/lib.rs
@@ -184,7 +184,7 @@ pub struct BamChunk<'a> {
 
 impl<'a> BamChunk<'a> {
     pub fn new(bam: bam::Records<'a, bam::Reader>, chunk_size: Option<usize>) -> Self {
-        let chunk_size = chunk_size.unwrap_or_else(|| current_num_threads() * 250);
+        let chunk_size = chunk_size.unwrap_or_else(|| current_num_threads() * 100);
         let bar = no_length_progress_bar();
         Self {
             bam,