diff --git a/org.hl7.fhir.r5/src/main/java/org/hl7/fhir/r5/elementmodel/JsonParser.java b/org.hl7.fhir.r5/src/main/java/org/hl7/fhir/r5/elementmodel/JsonParser.java
index d4b633e02..3878f0221 100644
--- a/org.hl7.fhir.r5/src/main/java/org/hl7/fhir/r5/elementmodel/JsonParser.java
+++ b/org.hl7.fhir.r5/src/main/java/org/hl7/fhir/r5/elementmodel/JsonParser.java
@@ -1,33 +1,33 @@
 package org.hl7.fhir.r5.elementmodel;
 
-/*
-  Copyright (c) 2011+, HL7, Inc.
-  All rights reserved.
-
-  Redistribution and use in source and binary forms, with or without modification, 
-  are permitted provided that the following conditions are met:
-
- * Redistributions of source code must retain the above copyright notice, this 
-     list of conditions and the following disclaimer.
- * Redistributions in binary form must reproduce the above copyright notice, 
-     this list of conditions and the following disclaimer in the documentation 
-     and/or other materials provided with the distribution.
- * Neither the name of HL7 nor the names of its contributors may be used to 
-     endorse or promote products derived from this software without specific 
-     prior written permission.
-
-  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND 
-  ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED 
-  WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 
-  IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, 
-  INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 
-  NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR 
-  PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, 
-  WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 
-  ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 
-  POSSIBILITY OF SUCH DAMAGE.
-
- */
+/*
+  Copyright (c) 2011+, HL7, Inc.
+  All rights reserved.
+
+  Redistribution and use in source and binary forms, with or without modification, 
+  are permitted provided that the following conditions are met:
+
+ * Redistributions of source code must retain the above copyright notice, this 
+     list of conditions and the following disclaimer.
+ * Redistributions in binary form must reproduce the above copyright notice, 
+     this list of conditions and the following disclaimer in the documentation 
+     and/or other materials provided with the distribution.
+ * Neither the name of HL7 nor the names of its contributors may be used to 
+     endorse or promote products derived from this software without specific 
+     prior written permission.
+
+  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND 
+  ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED 
+  WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 
+  IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, 
+  INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 
+  NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR 
+  PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, 
+  WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 
+  ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 
+  POSSIBILITY OF SUCH DAMAGE.
+
+ */
 
 
 
@@ -70,9 +70,15 @@ import com.google.gson.JsonElement;
 import com.google.gson.JsonNull;
 import com.google.gson.JsonObject;
 import com.google.gson.JsonPrimitive;
+import org.slf4j.LoggerFactory;
 
 public class JsonParser extends ParserBase {
 
+  static {
+    // Helpful for troubleshooting why this class is being loaded
+    LoggerFactory.getLogger(JsonParser.class).debug("Loading JsonParser class");
+  }
+
   private JsonCreator json;
   private Map<JsonElement, LocationData> map;
   private boolean allowComments;
diff --git a/org.hl7.fhir.r5/src/main/java/org/hl7/fhir/r5/elementmodel/XmlParser.java b/org.hl7.fhir.r5/src/main/java/org/hl7/fhir/r5/elementmodel/XmlParser.java
index 892080497..ae699cc78 100644
--- a/org.hl7.fhir.r5/src/main/java/org/hl7/fhir/r5/elementmodel/XmlParser.java
+++ b/org.hl7.fhir.r5/src/main/java/org/hl7/fhir/r5/elementmodel/XmlParser.java
@@ -75,12 +75,19 @@ import org.hl7.fhir.utilities.xhtml.XhtmlParser;
 import org.hl7.fhir.utilities.xml.IXMLWriter;
 import org.hl7.fhir.utilities.xml.XMLUtil;
 import org.hl7.fhir.utilities.xml.XMLWriter;
+import org.slf4j.LoggerFactory;
 import org.w3c.dom.Document;
 import org.w3c.dom.Node;
 import org.xml.sax.InputSource;
 import org.xml.sax.XMLReader;
 
 public class XmlParser extends ParserBase {
+
+  static {
+    // Helpful for troubleshooting why this class is being loaded
+    LoggerFactory.getLogger(XmlParser.class).debug("Loading JsonParser class");
+  }
+
   private boolean allowXsiLocation;
   private String version;
 
diff --git a/org.hl7.fhir.r5/src/main/java/org/hl7/fhir/r5/formats/FormatUtilities.java b/org.hl7.fhir.r5/src/main/java/org/hl7/fhir/r5/formats/FormatUtilities.java
index 242456397..95a092f05 100644
--- a/org.hl7.fhir.r5/src/main/java/org/hl7/fhir/r5/formats/FormatUtilities.java
+++ b/org.hl7.fhir.r5/src/main/java/org/hl7/fhir/r5/formats/FormatUtilities.java
@@ -3,34 +3,34 @@ package org.hl7.fhir.r5.formats;
 import java.io.FileNotFoundException;
 import java.io.IOException;
 
-/*
-  Copyright (c) 2011+, HL7, Inc.
-  All rights reserved.
-  
-  Redistribution and use in source and binary forms, with or without modification, 
-  are permitted provided that the following conditions are met:
-    
-   * Redistributions of source code must retain the above copyright notice, this 
-     list of conditions and the following disclaimer.
-   * Redistributions in binary form must reproduce the above copyright notice, 
-     this list of conditions and the following disclaimer in the documentation 
-     and/or other materials provided with the distribution.
-   * Neither the name of HL7 nor the names of its contributors may be used to 
-     endorse or promote products derived from this software without specific 
-     prior written permission.
-  
-  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND 
-  ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED 
-  WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 
-  IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, 
-  INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 
-  NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR 
-  PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, 
-  WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 
-  ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 
-  POSSIBILITY OF SUCH DAMAGE.
-  
- */
+/*
+  Copyright (c) 2011+, HL7, Inc.
+  All rights reserved.
+  
+  Redistribution and use in source and binary forms, with or without modification, 
+  are permitted provided that the following conditions are met:
+    
+   * Redistributions of source code must retain the above copyright notice, this 
+     list of conditions and the following disclaimer.
+   * Redistributions in binary form must reproduce the above copyright notice, 
+     this list of conditions and the following disclaimer in the documentation 
+     and/or other materials provided with the distribution.
+   * Neither the name of HL7 nor the names of its contributors may be used to 
+     endorse or promote products derived from this software without specific 
+     prior written permission.
+  
+  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND 
+  ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED 
+  WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 
+  IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, 
+  INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 
+  NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR 
+  PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, 
+  WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 
+  ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 
+  POSSIBILITY OF SUCH DAMAGE.
+  
+ */
 
 
 
@@ -63,6 +63,7 @@ POSSIBILITY OF SUCH DAMAGE.
 
 */
 
+import java.lang.reflect.InvocationTargetException;
 import java.math.BigDecimal;
 import java.net.URI;
 
@@ -117,24 +118,31 @@ public abstract class FormatUtilities {
   }
 
   public static ParserBase makeParser(FhirFormat format) {
-    switch (format) {
-    case XML : return new XmlParser();
-    case JSON : return new JsonParser();
-    case TURTLE : throw new Error("unsupported Format "+format.toString()); // return new TurtleParser();
-    case VBAR : throw new Error("unsupported Format "+format.toString()); // 
-    case TEXT : throw new Error("unsupported Format "+format.toString()); // 
-    }
-    throw new Error("unsupported Format "+format.toString());
+    return makeParser(format.name());
   }
   
   public static ParserBase makeParser(String format) {
-    if ("XML".equalsIgnoreCase(format)) return new XmlParser();
-    if ("JSON".equalsIgnoreCase(format)) return new JsonParser();
-    if ("TURTLE".equalsIgnoreCase(format)) throw new Error("unsupported Format "+format.toString()); // return new TurtleParser();
-    if ("JSONLD".equalsIgnoreCase(format)) throw new Error("unsupported Format "+format.toString()); // return new JsonLdParser();
-    if ("VBAR".equalsIgnoreCase(format)) throw new Error("unsupported Format "+format.toString()); // 
-    if ("TEXT".equalsIgnoreCase(format)) throw new Error("unsupported Format "+format.toString()); // 
-    throw new Error("unsupported Format "+format);
+    /*
+     * Note: In this class we're instantiating the parsers using reflection. This is because the
+     * XmlParser and JsonParser are huuuuuge classes and classloading them is quite expensive
+     * in cases where they won't actually ever be instantiated (such as when using the
+     * validator in HAPI FHIR)
+     */
+    try {
+      if ("XML".equalsIgnoreCase(format))
+        return (ParserBase) Class.forName("org.hl7.fhir.r5.formats.XmlParser").getConstructor().newInstance();
+      if ("JSON".equalsIgnoreCase(format))
+        return (ParserBase) Class.forName("org.hl7.fhir.r5.formats.JsonParser").getConstructor().newInstance();
+      if ("TURTLE".equalsIgnoreCase(format))
+        throw new Error("unsupported Format " + format.toString()); // return new TurtleParser();
+      if ("JSONLD".equalsIgnoreCase(format))
+        throw new Error("unsupported Format " + format.toString()); // return new JsonLdParser();
+      if ("VBAR".equalsIgnoreCase(format)) throw new Error("unsupported Format " + format.toString()); //
+      if ("TEXT".equalsIgnoreCase(format)) throw new Error("unsupported Format " + format.toString()); //
+      throw new Error("unsupported Format " + format);
+    } catch (ClassNotFoundException | NoSuchMethodException | InstantiationException | IllegalAccessException | InvocationTargetException e) {
+      throw new IllegalStateException("Failed to create parser", e);
+    }
   }  
 
   public static FhirFormat determineFormat(byte[] source) throws FHIRException {