Bar graph generated with Python has become unreadable. How to improve it? How to work with a dataset of more than 1 million rows?

Friends,

The following bar chart was generated (the first column of datasets is UNIX time):

ThePythoncode(version3.5)usedwasasfollows:

#-*-coding:utf-8-*-importmatplotlib.pyplotaspltimportmatplotlib.datesasdatesfromdatetimeimportdatetime,timedeltax=[]y=[]withopen("/Radhe/LabAbril2017Capturas/slices_calculos/winTime_10Abril_SemAtaques.csv") as f:
    for l in f:
        X,Y = l.split(",") #separador eh a virgula
        x.append(float(X))
        y.append(float (Y))

x1 = [datetime.fromtimestamp(int(d)) for d in x]
y_pos = [idx for idx, i in enumerate(y)]

plt.gca().xaxis.set_major_formatter(dates.DateFormatter('%m/%d/%Y %H:%M:%S'))

y1 = []
v = 0
y_sorted = sorted(y)
for i in y_sorted:
    if(abs(i-v > 50)):
        y1.append(i)
        v = i

plt.bar(y_pos, y, align='edge', color="blue", alpha=0.5, width=0.5) 

plt.title("Tamanho da janela TCP durante período sem ataques")
plt.ylabel("Tamanho da janela TCP")
plt.xlabel('Tempo')
plt.xticks(y_pos, x1, size='small',rotation=35, ha="right")
plt.yticks(y1)
plt.ylim(ymin=y_sorted[0]-200) # valor minimo do eixo y

plt.show()

Using the dataset winTime_10Abril_slowloris.csv, the chart was also bad:

ThedatasetwinTime_10Abril_SemAtaques.csvisavailablehere: link

The dataset winTime_10Abril_slowloris.csv is available here: link

How to make the chart more readable? Any more efficient way to do it? My next dataset has about 1 million rows .... It will take a long time ...

1 million line dataset (winTime_10Abril_sockstress.csv): link