I want to create a graph with large amounts of data, but I'm forced to quit.

import numpy as np
import pandas aspd
import matplotlib.pyplot asplt
import matplotlib.dates as mdates
import datetime
from datetime import datetime
from datetime import timedelta

startymdh='2018070100'
endymdh='2018070223'

ymdh = startymdh

# Graphing
config,ax=plt.subplots()

# x-axis range
ax.set_xlim(datetime.strptime(startymdh, '%Y%m%d%H', datetime.strptime(endymdh, '%Y%m%d%H')+timedelta(hours=1)))

ax.xaxis.set_major_formatter(mdates.DateFormatter('%m of %d'))

# Load files every hour
while ymdh<=endymdh:

    # x_data —Generates a list of 3600 elements every second from the start time
    x = pd.date_range(datetime.strptime(ymdh, '%Y%m%d%H',
                datetime.strptime(ymdh, '%Y%m%d%H') + timedelta(hours=1) - timedelta(seconds=1), 
                freq = 'S')

    #y_data—Generates a list of 3600 elements by generating random numbers between 0 and (1+hour)
    print (ymdh [8:10])
    y=np.random.randint(0,int(ymdh[8:10])+13600)

    #3 Plot
    ax.plot(x,y,color='C0')
    # set the variable to an hour later
    ymdhtmp = datetime.strptime(ymdh, '%Y%m%d%H') + timedelta(hours=1)
    ymdh=ymdhtmp.strftime('%Y%m%d%H')
else:
    # set the variable to an hour later
    ymdhtmp = datetime.strptime(ymdh, '%Y%m%d%H') + timedelta(hours=1)
    ymdh=ymdhtmp.strftime('%Y%m%d%H')
# Output File Name
plt.savefig('test.png')
plt.close()