Why is meta data 20 kb in a file

[schroef]

I was wondering why when saving metadata it adds 20kb in data. This seems quite a lot in file-size compared basically text.

attached are 2 test 1 with the meta-data 1 with.
compare-mdata.zip

I noticed its not much text
This is what i see in file info on photoshop for a file saved without Metadata

<x:xmpmeta xmlns:x="adobe:ns:meta/" x:xmptk="Adobe XMP Core 5.6-c140 79.160451, 2017/05/06-01:08:21        ">
   <rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#">
      <rdf:Description rdf:about=""
            xmlns:xmp="http://ns.adobe.com/xap/1.0/"
            xmlns:dc="http://purl.org/dc/elements/1.1/"
            xmlns:photoshop="http://ns.adobe.com/photoshop/1.0/">
         <xmp:CreatorTool>Adobe Photoshop CC (Macintosh)</xmp:CreatorTool>
         <xmp:CreateDate>2020-03-16T17:10:03-04:00</xmp:CreateDate>
         <xmp:ModifyDate>2020-03-16T17:10:04-04:00</xmp:ModifyDate>
         <xmp:MetadataDate>2020-03-16T17:10:04-04:00</xmp:MetadataDate>
         <dc:format>application/vnd.adobe.photoshop</dc:format>
         <photoshop:ColorMode>3</photoshop:ColorMode>
         <photoshop:ICCProfile>sRGB IEC61966-2.1</photoshop:ICCProfile>
      </rdf:Description>
   </rdf:RDF>
</x:xmpmeta>

This is a file with MetaData saved in photoshop

<x:xmpmeta xmlns:x="adobe:ns:meta/" x:xmptk="Adobe XMP Core 5.6-c140 79.160451, 2017/05/06-01:08:21        ">
   <rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#">
      <rdf:Description rdf:about=""
            xmlns:xmpMM="http://ns.adobe.com/xap/1.0/mm/"
            xmlns:stRef="http://ns.adobe.com/xap/1.0/sType/ResourceRef#"
            xmlns:stEvt="http://ns.adobe.com/xap/1.0/sType/ResourceEvent#"
            xmlns:xmp="http://ns.adobe.com/xap/1.0/"
            xmlns:dc="http://purl.org/dc/elements/1.1/"
            xmlns:photoshop="http://ns.adobe.com/photoshop/1.0/"
            xmlns:tiff="http://ns.adobe.com/tiff/1.0/"
            xmlns:exif="http://ns.adobe.com/exif/1.0/">
         <xmpMM:DocumentID>adobe:docid:photoshop:617b8582-05c7-5d40-99a6-0fd3740af304</xmpMM:DocumentID>
         <xmpMM:InstanceID>xmp.iid:adcead2f-d5cc-4c46-9abd-c8327f4bde64</xmpMM:InstanceID>
         <xmpMM:DerivedFrom rdf:parseType="Resource">
            <stRef:instanceID>xmp.iid:2d522c73-66ca-4938-8919-fa1b86fcfb4e</stRef:instanceID>
            <stRef:documentID>xmp.did:DF8CDCFA567311EABF37DD5B2804FDBC</stRef:documentID>
            <stRef:originalDocumentID>xmp.did:DF8CDCFA567311EABF37DD5B2804FDBC</stRef:originalDocumentID>
         </xmpMM:DerivedFrom>
         <xmpMM:OriginalDocumentID>xmp.did:DF8CDCFA567311EABF37DD5B2804FDBC</xmpMM:OriginalDocumentID>
         <xmpMM:History>
            <rdf:Seq>
               <rdf:li rdf:parseType="Resource">
                  <stEvt:action>saved</stEvt:action>
                  <stEvt:instanceID>xmp.iid:2d522c73-66ca-4938-8919-fa1b86fcfb4e</stEvt:instanceID>
                  <stEvt:when>2020-03-16T17:09:20-04:00</stEvt:when>
                  <stEvt:softwareAgent>Adobe Photoshop CC (Macintosh)</stEvt:softwareAgent>
                  <stEvt:changed>/</stEvt:changed>
               </rdf:li>
               <rdf:li rdf:parseType="Resource">
                  <stEvt:action>converted</stEvt:action>
                  <stEvt:parameters>from image/jpeg to application/vnd.adobe.photoshop</stEvt:parameters>
               </rdf:li>
               <rdf:li rdf:parseType="Resource">
                  <stEvt:action>derived</stEvt:action>
                  <stEvt:parameters>converted from image/jpeg to application/vnd.adobe.photoshop</stEvt:parameters>
               </rdf:li>
               <rdf:li rdf:parseType="Resource">
                  <stEvt:action>saved</stEvt:action>
                  <stEvt:instanceID>xmp.iid:adcead2f-d5cc-4c46-9abd-c8327f4bde64</stEvt:instanceID>
                  <stEvt:when>2020-03-16T17:09:20-04:00</stEvt:when>
                  <stEvt:softwareAgent>Adobe Photoshop CC (Macintosh)</stEvt:softwareAgent>
                  <stEvt:changed>/</stEvt:changed>
               </rdf:li>
            </rdf:Seq>
         </xmpMM:History>
         <xmp:CreatorTool>Adobe Photoshop CC (Macintosh)</xmp:CreatorTool>
         <xmp:CreateDate>2020-03-04T15:47:18-04:00</xmp:CreateDate>
         <xmp:ModifyDate>2020-03-16T17:09:20-04:00</xmp:ModifyDate>
         <xmp:MetadataDate>2020-03-16T17:09:20-04:00</xmp:MetadataDate>
         <dc:format>application/vnd.adobe.photoshop</dc:format>
         <photoshop:ColorMode>3</photoshop:ColorMode>
         <photoshop:ICCProfile>sRGB IEC61966-2.1</photoshop:ICCProfile>
         <tiff:ImageWidth>1920</tiff:ImageWidth>
         <tiff:ImageLength>1280</tiff:ImageLength>
         <tiff:BitsPerSample>
            <rdf:Seq>
               <rdf:li>8</rdf:li>
               <rdf:li>8</rdf:li>
               <rdf:li>8</rdf:li>
            </rdf:Seq>
         </tiff:BitsPerSample>
         <tiff:PhotometricInterpretation>2</tiff:PhotometricInterpretation>
         <tiff:Orientation>1</tiff:Orientation>
         <tiff:SamplesPerPixel>3</tiff:SamplesPerPixel>
         <tiff:XResolution>720000/10000</tiff:XResolution>
         <tiff:YResolution>720000/10000</tiff:YResolution>
         <tiff:ResolutionUnit>2</tiff:ResolutionUnit>
         <exif:ExifVersion>0221</exif:ExifVersion>
         <exif:ColorSpace>1</exif:ColorSpace>
         <exif:PixelXDimension>1920</exif:PixelXDimension>
         <exif:PixelYDimension>1280</exif:PixelYDimension>
      </rdf:Description>
   </rdf:RDF>
</x:xmpmeta>

It is more info, just wonder why that is 20kb in data