How do you perform CRUD operations in performance testing?

Hey guys,

I have an endpoint that has CRUD methods, to reuse the test data, I have to delete all data posted in the end. I want to make it as a test data auto-cleanup. 

So what I am doing right now is to chain those endpoints together, each of them is a test step of a test case, looks like below

- Test Suite
- Test Case 1
- Test Step 1: POST
- Test Step 2: GET
- Test Step 3: PATCH
- Test Step 4: DELETE

When I add this functional test case as a stress test, it looks like this: 

The issue is that when I run test with numbers of VUs, the TPS is lower for each request.
For example, I use 50VUs/sec, when I run single request as a test case, each of them can reach 50 TPS; when all 4 requests as a test case, I only got 20 TPS for each of them.

1. I am wondering what is the issue here? Do I set the test case wrong? The current test seems not to reflect the true behavior on the server side.

2. If I am not doing it right, then what is the optimized way to set test cases to perform CRUD in ReadyAPI? Is there a regular way to do it?

3. how is that TPS calculated in ReadyAPI?? does it use (number of counts/test duration)? 

4. BTW, the license I had is 250VUs, is this maybe an issue led by limitation of VUs?

Thanks,

Jess