I don't know if this is the most appropriate way to resolve this issue, but it worked for me. - After image is placed, I keep the layer selected and Command + J to duplicate it. (Work from this layer). - Go to top: Layer > Smart Objects > Rasterize - Once you've made your selection (with Lasso or Patch tool) you should be able to Edit Fill now. I'm not sure why Smart Objects can't use Content Aware Fill seamlessly, but this way might help you. ... View more

Some tips that have helped my lagging Illustrator issue (I previously posted a couple days ago): - I was using many Adobe PDFs in my Illustrator file, which are much larger in size -- Instead: using JPG, PNG or copy/pasted Vectors are much smaller (I am working on a portfolio which includes mockups and various types of files) - Saving, Closing and Reopening your Illustrator file seems to 'refresh' it a bit, making it run smoother Hope this helps! ... View more

I believe it has to do with how large the Illustrator file you're working on is, which is affected predominantly by the images you import into it. When I begin a new Ai file, the program works quite seamlessly. When you're working in strictly a vector file, it too runs pretty smoothly. However, when completing bigger projects and importing image files (whether Adobe PDF, JPG, PNG, etc), Illustrator starts to run extremely slow. I am having this problem while working on my portfolio, which includes various file types, including large image files. I don't have a solution at the moment, but I wonder if there's a way to shrink image file sizes that you import into your Illustrator file? Almost like using a 'zipped' version in your document as you work? If anyone knows if this is possible or has additional help, do tell! I too find it very nerve wracking to work when EVERY task/move in the program includes a 5-10+ second spinning pinwheel. Question -- Has anyone actually had these issues while working in a new/small/vector-only file? I haven't. The lag only comes when I'm working on extensive files. Also, specs: MacBook Pro w/ Retina (13 inch) - bought NEW Jan 2015 OS X El Capitan - Version 10.11.5 Processor: 2.6 GHz Intel Core i5 Memory: 8GB 1600 MHz DDR3 Startup Disk: Macintosh HD Graphics: Intel Iris 1536 MB Hope my input helps anyone pinpoint the problem! ... View more