There are a couple of things to keep in mind when you're facing speed issues with PlanSwift. 

Planswift in its current form is a 32-bit application, so it will have a limit of how much RAM it can actually use. Windows will cap PlanSwift at 2 gigs of RAM usage. Now when it starts to get close to its cap, it can bog down, and it can crash.  A couple of things can help with this: 

1.) Having at least 4 to 6 gigs of RAM; 4 gigs is the minimum we recommend.  

2) The more applications you have running alongside PlanSwift, the more RAM that is being used, and the more likely you are to run into a situation where PlanSwift bogs down.  So shut down any unnecessary programs that may be running alongside PlanSwift to minimize the RAM usage as much as possible. 

3) The more data you have inside of PlanSwift, the more RAM PlanSwift is going to use, so closing PlanSwift when you start to see it running slowly, should help to alleviate some of the slowness you're encountering.  

4) If you are working from a network location, the communication between PlanSwift and that network location will cause PlanSwift to slow down, you can move the file locally, work on the file, and then move it back, to alleviate speed issues. 

5) If PlanSwift is taking a long time to launch, or fully load when launching, you can go into your settings, select General, and uncheck the box for "Open the last job, when Planswift opens." this will help PlanSwift to launch a little bit quicker.  

Please also keep in mind, that this is what little we can do or suggest in situations of PlanSwift running slow. The developers are working on a 64-bit version, but it takes time and patience, and it is still a way off development wise.