问如何使knn更快？

EN

import os 
os.chdir(os.path.dirname(os.path.realpath(__file__)))

import tensorflow as tf
import pandas as pd
import numpy as np
from joblib import load, dump
import numpy as np
from scipy.spatial import distance
from sklearn.model_selection import train_test_split
from sklearn.neighbors import KNeighborsClassifier
from sklearn.model_selection import GridSearchCV
from sklearn.metrics import classification_report
from dtaidistance import dtw


window_length = 20
n = 5


X_train = load('X_train.pth').reshape(-1,20)
y_train = load('y_train.pth').reshape(-1)
X_test = load('X_test.pth').reshape(-1,20)
y_test = load('y_test.pth').reshape(-1)


#custom metric
def DTW(a, b):   
    return dtw.distance(a, b)


clf = KNeighborsClassifier(metric=DTW)
clf.fit(X_train, y_train)


#evaluate
y_pred = clf.predict(X_test)
print(classification_report(y_test, y_pred))