Add benchmark cases

[huandu]

Per #94, add some cases for performance.

[coveralls]

Coverage: 96.191%. Remained the same when pulling cc4fdfa on feature-benchmark into 1191d33 on master.

[huandu]

Help wanted in this PR. I know current test cases are incomplete. I need some one to contribute more and representative cases.

[shoriwe]

This PR has 2 years open. Any reason to not include it in main? These benchmarks are better than no benchmarks at all

[huandu]

@shoriwe I believe a fair performance benchmark should include test cases covering sufficiently typical application scenarios (rather than constructing cases with relatively obvious performance differences), fully considering the optimal implementations of various frameworks in these scenarios, and then conducting a side-by-side comparison. Currently, the testing in my PR is still quite inadequate, and there is no urgent demand for the performance benchmark itself. Therefore, it has been labeled as "help wanted" for an extended period without further progress. If you could provide assistance in this regard, it would be most welcome.