diff --git a/src/Library/AttackLibrary.hpp b/src/Library/AttackLibrary.hpp
index f506fd4..eb76230 100644
--- a/src/Library/AttackLibrary.hpp
+++ b/src/Library/AttackLibrary.hpp
@@ -11,7 +11,8 @@ namespace CreatureLib::Library {
         std::unordered_map<std::string, const AttackData*> _attacks;
 
     public:
-        AttackLibrary() = default;
+        AttackLibrary(size_t initialCapacity = 32)
+            : _attacks(std::unordered_map<std::string, const AttackData*>(initialCapacity)){};
 
         ~AttackLibrary() {
             for (auto attack : _attacks) {
diff --git a/src/Library/GrowthRates/GrowthRateLibrary.hpp b/src/Library/GrowthRates/GrowthRateLibrary.hpp
index 2a7a008..1d4b6c6 100644
--- a/src/Library/GrowthRates/GrowthRateLibrary.hpp
+++ b/src/Library/GrowthRates/GrowthRateLibrary.hpp
@@ -12,8 +12,11 @@ namespace CreatureLib::Library {
         std::unordered_map<std::string, GrowthRate*> _growthRates;
 
     public:
-        ~GrowthRateLibrary(){
-            for (auto gr: _growthRates){
+        GrowthRateLibrary(size_t initialCapacity = 10)
+            : _growthRates(std::unordered_map<std::string, GrowthRate*>(initialCapacity)) {}
+
+        ~GrowthRateLibrary() {
+            for (auto gr : _growthRates) {
                 delete gr.second;
             }
         }
diff --git a/src/Library/ItemLibrary.hpp b/src/Library/ItemLibrary.hpp
index d411de5..5b530e5 100644
--- a/src/Library/ItemLibrary.hpp
+++ b/src/Library/ItemLibrary.hpp
@@ -11,7 +11,8 @@ namespace CreatureLib::Library {
         std::unordered_map<std::string, const Item*> _items;
 
     public:
-        ItemLibrary() = default;
+        ItemLibrary(size_t initialCapacity = 32)
+            : _items(std::unordered_map<std::string, const Item*>(initialCapacity)){};
         ~ItemLibrary() { _items.clear(); }
 
         [[nodiscard]] const Item* GetItem(const std::string& name) const;
diff --git a/src/Library/SpeciesLibrary.hpp b/src/Library/SpeciesLibrary.hpp
index 186cf4e..1658338 100644
--- a/src/Library/SpeciesLibrary.hpp
+++ b/src/Library/SpeciesLibrary.hpp
@@ -11,7 +11,8 @@ namespace CreatureLib::Library {
         std::unordered_map<std::string, const CreatureSpecies*> _species;
 
     public:
-        SpeciesLibrary() = default;
+        SpeciesLibrary(size_t initialCapacity = 32)
+            : _species(std::unordered_map<std::string, const CreatureSpecies*>(initialCapacity)){};
 
         ~SpeciesLibrary() {
             for (auto s : _species)
diff --git a/src/Library/TypeLibrary.hpp b/src/Library/TypeLibrary.hpp
index 22758a2..f5aaa14 100644
--- a/src/Library/TypeLibrary.hpp
+++ b/src/Library/TypeLibrary.hpp
@@ -10,6 +10,8 @@ namespace CreatureLib::Library {
         std::vector<std::vector<float>> _effectiveness;
 
     public:
+        TypeLibrary(size_t initialCapacity = 20) : _types(std::unordered_map<std::string, uint8_t>(initialCapacity)) {}
+
         uint8_t GetTypeId(const std::string& s) const;
         float GetSingleEffectiveness(uint8_t attacking, uint8_t defensive) const;
         float GetEffectiveness(uint8_t attacking, const std::vector<uint8_t>& defensive) const;