Slow PDF generation with PHP+DomPDF

Question

I spent a while dealing with a really slow PDF generation process using DomPDF. After a lot of fiddling and googling, I eventually got a solution which I thought I\'d post i

Answer 1

SOLUTION:

After a lot of googling, trial and error, looking up a lot on Stackoverflow (none of the articles I found were really helpful), I figured out that it was bootstrap that was causing the issue.

I was using bootstrap for very basic layout management and I realized that linking the whole library (even the minified one) into the view that was sent to dompdf was overkill, but I didn't want to re-write the view file.

So, I took a different approach: Get the CSS definitions for the specific classes (6, maybe 7) my view was using and inline them in a <style> tag in the view

<style>
.row {
  margin-right: -15px;
  margin-left: -15px;
}
.col-xs-1, .col-sm-1, .col-md-1, .col-lg-1, .col-xs-2, .col-sm-2, .col-md-2, .col-lg-2, .col-xs-3, .col-sm-3, .col-md-3, .col-lg-3, .col-xs-4, .col-sm-4, .col-md-4, .col-lg-4, .col-xs-5, .col-sm-5, .col-md-5, .col-lg-5, .col-xs-6, .col-sm-6, .col-md-6, .col-lg-6, .col-xs-7, .col-sm-7, .col-md-7, .col-lg-7, .col-xs-8, .col-sm-8, .col-md-8, .col-lg-8, .col-xs-9, .col-sm-9, .col-md-9, .col-lg-9, .col-xs-10, .col-sm-10, .col-md-10, .col-lg-10, .col-xs-11, .col-sm-11, .col-md-11, .col-lg-11, .col-xs-12, .col-sm-12, .col-md-12, .col-lg-12 {
  position: relative;
  min-height: 1px;
  padding-right: 15px;
  padding-left: 15px;
}

.col-lg-12 {
    width: 100%;
}

.text-center {
  text-align: center;
}

body {
  font-family: Helvetica, Arial, sans-serif;
  font-size: 12px;
  line-height: 1.42857143;
  color: #333;
  background-color: #fff;
}
(...) the list goes on a little longer for some other bootstrap styles and other site-specific ones made by yours truly.
</style>

and remove bootstrap altogether from the view.

retesting, the results were astonishing: A 100 purchase order (100-page) PDF (less than 60 kB in size) which took between 30-60 seconds to be generated and streamed to the user before the change, is now being generated in less than half a second, which confirmed that linking bootstrap produces a HUGE overhead on dompdf which is probably unnecesary in 99% of use cases.

Hope this helps someone. It took quite a few days of work to figure this out.