Arduino CPU and RAM usage monitor. Credit goes to this post: https://www.reddit.com/r/arduino/comments/6uwkv5/cpu_and_ram_usage_monitor/

cpuRamUsage.cs

//CPU&RAM counter by Sharpy

using System;
using System.Windows.Forms;
using System.IO.Ports;
using System.Diagnostics;

namespace WindowsFormsApplication14
{
    public partial class Form1 : Form
    {
        SerialPort port;
        PerformanceCounter cpuCounter;
        PerformanceCounter ramCounter;

        public Form1()
        {
            InitializeComponent();
            cpuCounter = new PerformanceCounter("Processor", "% Processor Time", "_Total");
            ramCounter = new PerformanceCounter("Memory", "Available MBytes");
        }

        private void button1_Click(object sender, EventArgs e)
        {
            port = new SerialPort(textBox1.Text, 9600);
            port.Open();
        }

        private void button2_Click(object sender, EventArgs e)
        {
            Timer t = new Timer();
            t.Interval = 2000;
            t.Start();
            t.Tick += (ev, s) => { giveStats(); };
        }
        public string getCurrentCpuUsage
        {
            get
            {
                return (int)cpuCounter.NextValue() + "%";
            }
        }

        public string getAvailableRAM
        {
            get
            {
                return ramCounter.NextValue() + "MB";
            }
        }

        public void giveStats()
        {
                port.WriteLine((checkBox1.Checked ? "CPU:" + getCurrentCpuUsage : string.Empty));
                port.WriteLine((checkBox3.Checked ? "RAM:" + getAvailableRAM : string.Empty));
        }

        private void button3_Click(object sender, EventArgs e)
        {
            port.Close();
        }
    }
}

cpuRamUsage.ino

/////////////////////////////////////////
//Universal serial comunicator by Sharp//
/////////////////////////////////////////

#include <gfxfont.h>
#include <Adafruit_SSD1306.h>

#define OLED_RESET 4
Adafruit_SSD1306 display(OLED_RESET);
String val;
int preval;
int x = 0, y = 0;

void cleart(){
    display.clearDisplay();
    display.display();
}
void setup()
{
Serial.begin(9600);
display.begin(SSD1306_SWITCHCAPVCC, 0x3C); 
display.clearDisplay();
display.setRotation(2);
}

void loop()
{
  if (Serial.available()>0)
  {
    val = Serial.readString();
    display.setTextSize(2);
    display.setTextColor(WHITE);
    display.setCursor(x, y);
    display.print(val);
    display.display();
  }
  else{
    display.clearDisplay();
  }
}