BLE is not designed for high bandwidth, its about using as less energy as possible. A typical data rate is about 10kb/s. Anaren has a nice description: https://atmosphere.anaren.com/wiki/Data_rates_using_BLE
If you use larger packet sizes you get up to 200kb/s, but it won't get much faster than that.
Actually, 10KB/s should be enough for me.
Can you tell me more information about how to use larger packet for a faster speed? And should I still use CyBle_GattsNotification to send data as part of attribute notification?
Look at the 100 BLE projects list. There is one entry about throughput: http://www.cypress.com/blog/100-projects-100-days/project-024-ble-throughput-pushing-limits
and one with a UART-over BLE bridge: http://www.cypress.com/blog/100-projects-100-days/project-020-uart-ble-bridge