Large latency for write operation

[qh-huang]

I tried with my android app to write 1000 bytes to TestCharacteristic, and it takes about 500 ms; I did the same thing to another device which equipped a Bluetooth module, it took only 200 ms.

Is this difference caused by language (as Python is slower) ? or is there other factors that could cause the latency (like MTU)?

If it's about MTU setting, how could I get/set/modify MTU size?

Thank you.