LCD screen slow to change pages

I'm working on a project that has an LCD screen, 20x4, that has two pages controlled by a push button. It works but, sometimes the screen changes with a simple button push and sometimes it won't change unless I hold the button down. Sometimes multiple pushes changes the screen every time. It seems like the more times I change it the slower it gets. Am I just bogging the Arduino down? This is part of a larger project but, I like to make sure smaller bits work before adding them together. 

and code. I'm terrible at coding but, it does work.

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#include "Wire.h"
#include "Adafruit_LiquidCrystal.h"
#include "SDL_Arduino_INA3221.h"
SDL_Arduino_INA3221 ina3221;
#include <DallasTemperature.h>
// -------------------------------the three channels of the INA3221 for voltage
#define HOUSE_BATTERY 1
#define CHARGER_CHANNEL 2
#define START_BATTERY_CHANNEL 3

Adafruit_LiquidCrystal lcd(0);
//===============================Temperature
#define ONE_WIRE_BUS 7 //pin for DS18B20
OneWire oneWire(ONE_WIRE_BUS);
DallasTemperature sensors(&oneWire);
int analogInput = A1;
float vout = 0.0;
float vin = 0.0;
float R1 = 30000.0; //
float R2 = 7500.0; //
int value = 0;

//------------------------------------Counter to change positions of pages

int page_counter = 1 ; //To move beetwen pages

//-------Pins-----
int up = 8; //menu button

//---------Storage debounce function-----
boolean current_up = LOW;
boolean last_up = LOW;
boolean last_down = LOW;
boolean current_down = LOW;

void setup() {
lcd.begin(20, 4);
ina3221.begin();
sensors.begin();
}

//---- De-bouncing function for all buttons----
boolean debounce(boolean last, int pin)
{
boolean current = digitalRead(pin);
if (last != current)
{
delay(2);
current = digitalRead(pin);
}
return current;
}

void loop() {
float busvoltage1 = 0;
busvoltage1 = ina3221.getBusVoltage_V(HOUSE_BATTERY);
float busvoltage2 = 0;
busvoltage2 = ina3221.getBusVoltage_V(CHARGER_CHANNEL);
float busvoltage3 = 0;
busvoltage3 = ina3221.getBusVoltage_V(START_BATTERY_CHANNEL);

current_up = debounce(last_up, up); //Debounce for Up button

//----Page counter function to move pages----

//Page Up
if (last_up == LOW && current_up == HIGH) { //When up button is pressed
lcd.clear(); //When page is changed, lcd clear to print new page
if (page_counter < 2) { //Page counter never higher than 3(total of pages)
page_counter = page_counter + 1; //Page up

}
else {
page_counter = 1;
}
}

last_up = current_up;

last_down = current_down;

//------- Switch function to write and show what you want---//
switch (page_counter)

{

case 1: { //Design of home page 1
lcd.setCursor(0, 0);
lcd.print("House Batt");
lcd.setCursor(13, 0);
lcd.print(busvoltage1);
lcd.setCursor(0, 1);
lcd.print("Charge Batt");
lcd.setCursor(13, 1);
lcd.print(busvoltage2);
lcd.setCursor(0, 2);
lcd.print("Start Batt");
lcd.setCursor(13, 2);
lcd.print(busvoltage3);
}
break;

case 2: { //Design of page 2
sensors.requestTemperatures();
float temperature1 = sensors.getTempFByIndex(0);
lcd.setCursor(0, 0);
lcd.print("Battery Temp");
lcd.setCursor(13, 0);
lcd.print(sensors.getTempFByIndex(0));

float temperature2 = sensors.getTempFByIndex(1);
lcd.setCursor(0, 1);
lcd.print("Cabin Temp");
lcd.setCursor(13, 1);
lcd.print(sensors.getTempFByIndex(1));

float temperature3 = sensors.getTempFByIndex(2);
lcd.setCursor(0, 2);
lcd.print("Heat Temp");
lcd.setCursor(13, 2);
lcd.print(sensors.getTempFByIndex(2));

float temperature4 = sensors.getTempFByIndex(3);
lcd.setCursor(0, 3);
lcd.print("Outside Temp");
lcd.setCursor(13, 3);
lcd.print(sensors.getTempFByIndex(3));

}
break;

}//switch end

}//loop end