Why TF waiting a lot of time before start work?

Hi, everyone!

I need help with strange behaveor of TF. Before start training network program waiting 20 minutes. During of tthis pouse programm use only 20% CPU, without GPU. How to fix it?

input_train, output_train, input_test, output_test = DataManager.GetDataSet(10, 2, 10000, 3, True)

model = Sequential([
    keras.layers.Conv1D(input_shape=(30000, 1), filters = 64, kernel_size = 50, strides=10, padding='same', activation='relu'),
    keras.layers.MaxPool1D(pool_size=10,strides=3),
    keras.layers.Conv1D(filters = 128, kernel_size = 50, strides=10, padding='same', activation='relu'),
    keras.layers.MaxPool1D(pool_size=10,strides=10),
    keras.layers.Flatten(),
    keras.layers.Dense(128, activation="relu"),
    keras.layers.Dense(1, activation="softmax")
])

model.compile(
    optimizer='adam',
    loss='sparse_categorical_crossentropy',
    metrics=['accuracy']
)

model.fit(input_train, output_train, epochs=5)
model.evaluate(input_test, output_test)