Mozilla developer Nicholas Nethercote is taking steps to make PDFs in Firefox slimmer.

Earlier this year, Nethercote optimized the PDF viewing process for Firefox with pdf.js, a new PDF viewer that uses HTML canvas elements to render each PDF page. Those “canvas” elements can be millions of pixels in size.

While Nethercote’s enchancements greatly improved rendering on Linux, the changes left PDF viewing slow for OS X users. The reason for this, Nethercote says, is that Firefox on Linux doesn’t store this kind of data within the Firefox process, but Firefox for Mac does.

He’s applied four patches to the problem, and now pdf.js caches fewer canvases and can dispose of the excess. So far, the patches are live in the master pdf.js repository, and they’ll be integrated into Firefox code in time for the release of Firefox 33 in mid-October.

Firefox pdf js