diff --git a/src/ftrl.rs b/src/ftrl.rs
index 960fc70..818c3bd 100644
--- a/src/ftrl.rs
+++ b/src/ftrl.rs
@@ -27,9 +27,9 @@ impl FTRL {
             beta,
             lambda1,
             lambda2,
-            z: HashMap::new(),
-            n: HashMap::new(),
-            weights: HashMap::new(),
+            z: HashMap::with_capacity(8192),
+            n: HashMap::with_capacity(8192),
+            weights: HashMap::with_capacity(8192),
         }
     }
 
diff --git a/src/identifiers.rs b/src/identifiers.rs
index daebfdc..42ccf15 100644
--- a/src/identifiers.rs
+++ b/src/identifiers.rs
@@ -104,8 +104,8 @@ impl Identifier {
         Self {
             name: name.to_string(),
             pass_through: None,
-            obj_to_id: HashMap::new(),
-            id_to_obj: Vec::new(),
+            obj_to_id: HashMap::with_capacity(8192),
+            id_to_obj: Vec::with_capacity(8192),
         }
     }
 
diff --git a/src/interactions.rs b/src/interactions.rs
index 561baa3..fe5c969 100644
--- a/src/interactions.rs
+++ b/src/interactions.rs
@@ -19,8 +19,8 @@ impl UserItemInteractions {
         let decay_rate = decay_in_days.map(|days| 1.0 - (E.ln() / days));
 
         UserItemInteractions {
-            interactions: HashMap::new(),
-            all_item_ids: HashSet::new(),
+            interactions: HashMap::with_capacity(8192),
+            all_item_ids: HashSet::with_capacity(8192),
             min_value,
             max_value,
             decay_rate,