Cloudmersive provides an API Benchmark tool for generating a CSV file with API response time in seconds:

https://github.com/Cloudmersive/Cloudmersive.Benchmark.Tool

The tool is open source and implemented in C#. To use the tool, modify the line 8 variable "Path" to point to a folder containing one or more files you wish to test. Also, modify line 18 to specify your API key. If you wish to use Cloudmersive Managed Instance, you can also set the Basepath to point to your Managed Instance.