It sucks that this issue is coming up for others as it’s a real hamper on production and efficiency but I’m glad in the sense that it isn’t only me experiencing these issues. I as well am using a Macbook but I had an external USB mouse connected. I haven’t tried using it with the trackpad. (ick! hehe) I had thought about it to see if the problem persisted but now that you’ve replied I’m going to give it a shot but I foresee the same issues.
Hopefully we can get an admin or staff reporting on this issue or providing some sort of fix to get by until an official hot fix can be released. I’m still not sure if it’s due to low frame rate but that shouldn’t be an issue with Scalability being on Low and still experiencing the problems. Like you I will probably stick to 4.3 for now until this gets resolved whereas it’s taking me twice the amount of time as normal to do anything.