Is this for the new version of the app that recently came out? Version 25. Could you check your task manager while things are slow to see what's consuming resources?

We haven't received any reports of the app having that effect on anyone's computer. The new app should be significantly faster than the last, but given that we can't control the software that might be on someone's computer, we can't anticipate all issues. If I had to guess I would say it's probably virus scanner you have on your computer. 

Thanks

I see you're using Windows 7 - how many cores do your CPU have?