I have a 2011 13' i5 8GB MBP, the user has always used Preview to combine PDFs as part of her work flow. To the best of my knowledge her process hasn't changed, however Preview is now failing to process this, it just locks up and fails to respond. A force quit show it has partially combined the PDF's but only ever adds the first page of the inserted file.
We have a text only PDF (roughly ~35KB) and a 2 page scanned document (~750KB).
The first file is opened in preview, we hit 'edit > insert from file' and choose the larger scanned file and the whole lot locks up.
This worked before the update to macOS (she'd been holding off for other reasons that are now resolved, hence updating only this weekend).
I see lots of people reporting performance issues with PDF's after the transition to Yosemite, with lots of people complaining of unresolved bugs around the performance of this app but very little with regards to this latest version.
How can I measure what might be slowing this down or decide if I need to look to another program / tool to perform this work?
The first thing to do is check on some common sense items:
This procedure is very general and catches 4/5 of the issues we have at work with our Mac. It’s not specific to preview, but will ensure you don’t look at a specific app when you actually have a system issue slowing down your Mac.