Some time ago, about 7 months, I had to build a service that creates a PDF document from HTML. The library of choice was IronPDF. Creating PDF documents with this library is a breeze, but we stumbled across a small issue.

The HTML-to-PDF-converter-service is hosted inside an Azure Function, for reasons. We noticed creating the documents took quite a lot of time. After inspecting the allocated instances we discovered both the CPU and Memory were constantly spiking to maximum capacity. That’s not good.
What made things worse, the generation sometimes took up to 37 minutes to complete! That’s not acceptable if your customers are waiting for the document.

This service was deployed on Windows instances, as it’s the default.
Because Linux is more lightweight compared to Windows, we started doing a test if the document rendering would be faster on Azure Functions hosted on Linux instances. The results were staggering!
On the Linux instances, all of the documents being generated never took more than 3 minutes to complete (99th percentile) and the used resources were less. We were still using a lot of CPU and memory, but acceptable levels. That’s the moment we decided to go forward using Linux hosted Azure Functions for this part of the system.
We just had to find out how to deploy them.