Find the bottleneck of your model.

keras_bottleneck.py

import tensorflow as tf
from tensorflow.python.client import timeline
import keras

tl = timeline.Timeline(run_metadata.step_stats)
ctf = tl.generate_chrome_trace_format()

run_options = tf.RunOptions(trace_level=tf.RunOptions.FULL_TRACE)
run_metadata= tf.RunMetadata()

model = ...
model.compile(..., options=run_options, run_metadata=run_metadata)

model.fit(...)

with open("output.json", 'w') as f:
    f.write(ctf)