REST API performance over HTTP and HTTPS compared

Published on October 28th, 2021

We wanted to find out how would the performance of a REST API be impacted if it is called over HTTP vs. HTTPS.

Here is how we setup this simple performance test:

Created and launched a linux based VM in the Cloud
Deployed the application containing the REST API code on to the Linux VM
Assigned a public IP address to the Linux VM for direct API calls over HTTP
Created Load Balancer in the Cloud with TLS/SSL termination and configured it to direct the request to the Linux VM (for API calls over HTTPS)
Used JMeter to run the tests to analyze the difference in performance when the REST API is invoked over HTTP vs HTTPS
Call the API 120 times over HTTP and 120 times over HTTPS to get the average response time

The performance tests results are recorded in the tables below

Performance Test # 1 Results

Observation: Fastest response was received over HTTP but the average response was exactly the same for both HTTP and HTTPS

	HTTP	https
Number of Concurrent Requests	1	1
Total API Calls made	120	120
API Response Size (bytes)	170856	170856
Total Time to make 120 API Calls (seconds)	22	22
Average API Response Time (milliseconds)	190	190
Fastest API Response Time (milliseconds)	28	41
Slowest API Response Time (milliseconds)	308	302

Performance Test # 2 Results

Observation: Fastest response was received over HTTPS and the average API response time over HTTPS was better as well

	HTTP	https
Number of Concurrent Requests	2	2
Total API Calls made	120	120
API Response Size (bytes)	170856	170856
Total Time to make 120 API Calls (seconds)	22	22
Average API Response Time (milliseconds)	379	378
Fastest API Response Time (milliseconds)	43	42
Slowest API Response Time (milliseconds)	504	511

Performance Test # 3

Observation: Fastest response was received over HTTPS but the average response time was the same for both

	HTTP	https
Number of Concurrent Requests	3	3
Total API Calls made	120	120
API Response Size (bytes)	170856	170856
Total Time to make 120 API Calls (seconds)	22	22
Average API Response Time (milliseconds)	567	567
Fastest API Response Time (milliseconds)	53	47
Slowest API Response Time (milliseconds)	720	717

Performance Test # 4

Observation: Average response time over HTTPS was better than HTTP

	HTTP	https
Number of Concurrent Requests	4	4
Total API Calls made	120	120
API Response Size (bytes)	170856	170856
Total Time to make 120 API Calls (seconds)	22	22
Average API Response Time (milliseconds)	755	753
Fastest API Response Time (milliseconds)	45	45
Slowest API Response Time (milliseconds)	915	920

Conclusion

Based on the environment setup and results presented above, we concluded that HTTPS did not impact the performance of our REST API negatively, if TLS/SSL termination is handled by the Cloud based Load Balancer.

Infact, Test # 2 and 4 indicate that HTTPS average response time was better than the average response time over HTTP.

You can contact us at info@apinoncloud.com if you have any questions or comments about the information presented in this post.