I would say this application I have ever used to use two accounts at a time, I use dual accounts of whats app, Facebook, Instagram and I did not found any lag within 2 months of use, totally satisfying application with an impressive layout.
Parallel space is very much useful when you are not happy with a single account and need one more account, I loved the features because it creates a shortcut on the window to access the another parallel account.
Everybody should use this application, if they are not happy with a single account of whats app, Facebook, twitter etc.