I've noticed that the last few days Sketch has been eating up more app memory in RAM than normal. I have a 2015 MBP with 16GB of RAM and normally have a have 6-8 free gigs of RAM with my usual programs open. Lately it's dropped to about 2 or below. The files I work with aren't very big. Some of my other programs give me the beach ball with clicking on stuff like Outlook or Slack as a result. When I close Sketch, things go back to normal. Was wondering if anyone else has experience something similar.
I've definitely noticed an increase in RAM dependancy, it's been bothering me quite a bit but then I put it down to the relatively large images I've been using in mocks.
Perhaps turn auto-save off for the time being? Are you using iCloud/Dropbox/Drive by any chance? I noticed that once I paused InSync (Drive), things started to ease up a little.
Perhaps it's the 'undo's'? I know they live in RAM. Would be good to get some light shone upon this situation.