There are no circles in PDF. Thought you saw a circle in a PDF file? Nope, you saw a series of Beziér cubic splines approximating a circle. This has never been a problem for me before, and I’ve cheerfully instructed the PDF::API2::Lite module to render dozens, nay hundreds of these “circles” on a single page, and it has always worked.
Then I tried rendering a few tens of thousands of them, and heard the fans on my laptop spin up. PDF::API2 is a pure-perl module, you see, and Perl is not, shall we say, optimized for trig. PDF::Haru, on the other hand, is a thin wrapper around Haru, which is written in C. Conversion took only a few minutes, which is about a tenth of the time the script would have needed to finish rendering, and the new version took 15 seconds to render a 1:50,000,000 scale Natural Earth basemap and all the data points.
I ended up abandoning “circles” for squares anyway, though, because PDF viewers aren’t happy with them in those quantities, either. Still faster to do it with PDF::Haru, so the time wasn’t wasted.
As a bonus, Haru has support for rendering vertical text in Japanese. I can think of a few uses for that in my other projects.
(I should note that it’s not useful for every project, and in most respects PDF::API2 is a more complete implementation of the spec, but for straightforward image rendering, it’s a lot faster. Development seems to have mostly stopped as well, so if it doesn’t do what you want today, it likely never will)