the file of the tpot.fitted_pipeline_ is very large

Hi tpot team,
Now,I can save the tpot.fitted_pipeline_ and load it,but the file of the tpot.fitted_pipeline_ is very large.it is relate to training data,the more data, the bigger the tpot.fitted_pipeline_.My training data size is 618kKB,but the saved tpot.fitted_pipeline_ size is 7828KB.
the following code:
save:
with open("./model.pickle","wb") as f:
pickle.dump(tpot.fitted_pipeline_,f)
load:
with open("./model.pickle","rb")as f:
model= pickle.load(f)
because the size of tpot.fitted_pipeline_ is very large,load it is very slow.
how can i reduce the size.