Small C# program takes up too much memory

I have a small C# program (about 400 lines of code) that is only 28kb
after compiled.

However when it runs (takes a whole 5 seconds) it takes up nearly 20MB
of memory and I don't see why.

Some of the assembly I used:

using System;
using System.Collections.Generic;
using System.Windows.Forms;
using System.Xml.Serialization;
using System.IO;
using System.Diagnostics;
using System.Management;

The program read (de-serialize) a XML file, then generate a list. Then
the program read through the event log and see if anything match the
list.

Is there anyway I can reduce the memory usage?

.

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