Thanks for letting me know. This is a well known issue – not that it crashes, but that it turns increasingly slow the more you lasso something, stamp it and lasso it again, and so on. If you use the lasso/cutter many times on the same drawing, the data builds up and it ends up slowing down and taking up a lot of memory. You must hav gotten a warning about this – a window pops up and explains this and how to remedy it. I hope you got that warning?
In the next version we are going to release (Alpha 8) we have done much more to help people in your situation. You will then be able to “collapse” the data and therefore get everything running a full speed again.
Here’s how the warning looks in our current internal version. This might be subject to change, but basically, this is it:
Right now, with your current version (Alpha 7), I would trace your problematic drawings/frames on to new blank frames and delete the old ones. Then you’ll see you filesize go way down and your lasso work a full speed again.
When we release Alpha 8, make sure to download that, to get the Collapse button you see above. 😉
I hope this helps you.