PythonでDataFrameのfor文の高速化

Question

import pandas as pd

pd.set_option('display.unicode.east_asian_width', True)
df = pd.read_csv("./csv/sorted3.csv")

for i in range(20001, 291421): # 60002
    print(df.loc[i, "name"])
    k = 0
    for j in range(i-1, i-20000, -1):
        if df.loc[j, "name"] == df.loc[i, "name"]:
            print(i, j)
            if pd.isna(df.loc[i, "1p_result"]) == True:
                df.loc[i, "1p_result"] = df.loc[j, "result"]
            elif pd.isna(df.loc[i, "1p_result"]) == False and pd.isna(df.loc[i, "2p_result"]) == True:
                df.loc[i, "2p_result"] = df.loc[j, "result"]
            elif pd.isna(df.loc[i, "1p_result"]) == False and pd.isna(df.loc[i, "2p_result"]) == False and pd.isna(df.loc[i, "3p_result"]) == True:
                df.loc[i, "3p_result"] = df.loc[j, "result"]
            if pd.isna(df.loc[i, "1p_speed"]) == True:
                df.loc[i, "1p_speed"] = df.loc[j, "distance"] / df.loc[j, "time"]
            elif pd.isna(df.loc[i, "1p_speed"]) == False and pd.isna(df.loc[i, "2p_speed"]) == True:
                df.loc[i, "2p_speed"] = df.loc[j, "distance"] / df.loc[j, "time"]
            elif pd.isna(df.loc[i, "1p_speed"]) == False and pd.isna(df.loc[i, "2p_speed"]) == False and pd.isna(df.loc[i, "3p_speed"]) == True:
                    df.loc[i, "3p_speed"] = df.loc[j, "distance"] / df.loc[j, "time"]
            k += 1
        if k == 3:
            break

df[20001:291421].to_csv("./csv/dataset.csv", index=False)

date,place,race,course,distance,surface,weather,total,number,name,age,weight,weight_diff,result,time,time_diff,popularity,odds,abnormal,1p_result,2p_result,3p_result,1p_speed,2p_speed,3p_speed
2015-01-04,京都,1,ダ,1200,重,曇,16,1,ディアエナ,3,510.0,2.0,2,72.4, 0.4,2.0,4.3,0,,,,,,
2015-01-04,中山,8,ダ,1200,良,晴,16,7,ナスケンリュウジン,4,460.0,0.0,10,72.7, 1.1,13.0,55.3,0,,,,,,
2015-01-04,中山,8,ダ,1200,良,晴,16,8,ヒカリマサムネ,5,468.0,4.0,2,71.6, 0.0,7.0,21.4,0,,,,,,
2015-01-04,中山,8,ダ,1200,良,晴,16,9,サンライズマーチ,5,484.0,0.0,9,72.6, 1.0,2.0,6.0,0,,,,,,
.
.
.

こちらのコードを高速化したいのですが、どなたか知恵を貸していただけませんか？