Sorry to hear that. The font issue has been around for some time, so it isn’t the cause of your issue. I haven’t been able to reproduce the sluggishness myself, can you let us know which project you’re having issues with and we can take a closer look. Thanks!
One thing that can make the editor feel sluggish is having it connected to a tab you have opened with “Show Live”. That tab will be refreshed every time you type in the code, and that causes some delays. You can turn this off by unchecking “Refresh App on Changes” under your avatar menu in the upper right.