Clear sockets perform worse than TLS socket in some cases

<!-- Thank you for reporting a possible bug in Node.js. Please fill in as much of the template below as you can. Version: output of `node -v` Platform: output of `uname -a` (UNIX), or version and 32 or 64-bit (Windows) Subsystem: if known, please specify the affected core module name If possible, please provide code that demonstrates the problem, keeping it as simple and free of external dependencies as you can. --> * **Version**: v13.0.0-pre * **Platform**: Linux tufopad 4.15.0-48-generic #51-Ubuntu SMP Wed Apr 3 08:28:49 UTC 2019 x86_64 x86_64 x86_64 GNU/Linux * **Subsystem**: net <!-- Please provide more details below this comment. --> While writing and performing tests for [this issue](https://github.com/nodejs/node/issues/20263) opened by @alexfernandez and [fixed](https://github.com/nodejs/node/pull/27861) by @jmendeth, I noticed that in some cases, clear connections seem to perform worse than TLS connections, specially after the fix that enhances significantly the performance of the TLS connections. I will patch the existing secure-pair benchmark test to expose the issue. The performance of clear connections seems to be the same across node versions (I've tested it in node 8, 10 and 13-pre). This means that this issue is not a regression, but an enhancement, and the fix needed is probably very similar to the one that solved the secure-pair performance issue.