diff --git a/src/main/java/proteomics/Types/ChainEntry.java b/src/main/java/proteomics/Types/ChainEntry.java
index 123b4e0..96c30ee 100644
--- a/src/main/java/proteomics/Types/ChainEntry.java
+++ b/src/main/java/proteomics/Types/ChainEntry.java
@@ -10,7 +10,6 @@ public class ChainEntry {
     public final boolean n_term;
     public final boolean c_term;
     public final int binaryModType;
-    private final String toString;
 
     public ChainEntry(String seq, float chain_mass, Set<Short> link_site_set, boolean n_term, boolean c_term, int binaryModType) {
         this.seq = seq;
@@ -19,7 +18,6 @@ public ChainEntry(String seq, float chain_mass, Set<Short> link_site_set, boolea
         this.n_term = n_term;
         this.c_term = c_term;
         this.binaryModType = binaryModType;
-        toString = seq + "-" + binaryModType;
     }
 
     @Override
@@ -31,8 +29,4 @@ public boolean equals(Object other) {
             return false;
         }
     }
-
-    public String toString() {
-        return toString;
-    }
 }
\ No newline at end of file
diff --git a/src/main/java/proteomics/Types/SpectrumEntry.java b/src/main/java/proteomics/Types/SpectrumEntry.java
index cfba351..ce3730d 100644
--- a/src/main/java/proteomics/Types/SpectrumEntry.java
+++ b/src/main/java/proteomics/Types/SpectrumEntry.java
@@ -12,7 +12,6 @@ public class SpectrumEntry {
     public final int precursor_charge;
     public final String mgfTitle;
     public Map<Double, Double> originalPlMap;
-    private final String to_string;
 
     public SpectrumEntry(int scan_num, String spectrum_id, float precursor_mz, float precursor_mass, int precursor_charge, float rt, Map<Double, Double> originalPlMap, float linker_mass, String mgfTitle) {
         this.scan_num = scan_num;
@@ -24,11 +23,6 @@ public SpectrumEntry(int scan_num, String spectrum_id, float precursor_mz, float
         this.rt = rt;
         this.mgfTitle = mgfTitle;
         this.originalPlMap = originalPlMap;
-        to_string = this.scan_num + "(charge=" + precursor_charge + ",mass=" + precursor_mass + ",peakNum=" + originalPlMap.size() + ")";
-    }
-
-    public String toString() {
-        return to_string;
     }
 
     public int hashCode() {
diff --git a/src/main/java/proteomics/Types/VarModParam.java b/src/main/java/proteomics/Types/VarModParam.java
index 3de2df5..b21c180 100644
--- a/src/main/java/proteomics/Types/VarModParam.java
+++ b/src/main/java/proteomics/Types/VarModParam.java
@@ -5,12 +5,14 @@ public class VarModParam {
 
     public final float modMass;
     public final char aa;
-    public final String toString;
+    private final String toString;
+    private final int hashCode;
 
     public VarModParam(float modMass, char aa) {
         this.modMass = modMass;
         this.aa = aa;
         toString = modMass + "@" + aa;
+        hashCode = toString.hashCode();
     }
 
     public String toString() {
@@ -18,7 +20,7 @@ public String toString() {
     }
 
     public int hashCode() {
-        return toString.hashCode();
+        return hashCode;
     }
 
     public boolean equals(Object other) {
diff --git a/src/main/java/proteomics/Types/VarSequence.java b/src/main/java/proteomics/Types/VarSequence.java
index 914c609..99ef1a8 100644
--- a/src/main/java/proteomics/Types/VarSequence.java
+++ b/src/main/java/proteomics/Types/VarSequence.java
@@ -7,12 +7,14 @@ public class VarSequence {
     public final short linkSite;
     public final int binaryModType;
     private final String toString;
+    private final int hashCode;
 
     public VarSequence(String seq, short linkSite, int binaryModType) {
         this.seq = seq;
         this.linkSite = linkSite;
         this.binaryModType = binaryModType;
         toString = seq + "-" + linkSite + "-" + binaryModType;
+        hashCode = toString.hashCode();
     }
 
     public boolean equals(Object other) {
@@ -29,6 +31,6 @@ public String toString() {
     }
 
     public int hashCode() {
-        return toString.hashCode();
+        return hashCode;
     }
 }