TLS Performance in Java?

I see the TLS implementation in Java doesn't use JNI at all. A native implementation for TLS should be faster IMO. So I guess maybe JNI itself is too expensive, compared to the benefits of native TLS.

So, how about the TLS performance in Java, or should I have to avoid it whenever possible?

Why do you think that native Java code is slow? It is compiled to machine code, just as your native implementation would be.

For now, just use the native TLS, and if it proves to be a bottleneck, you can still optimize it. Keep it simple.

I did a study on this a couple of years ago. 1700 data points. TLS over the Internet is 1/3 the speed of plaintext. Surprising? The bottleneck is the network, not TLS.