Hi
Due to the database structure, AccountRight 2017 may perform differently to the AccountRight Classic range. In terms of improving that speed, there is no magic bullet to improving the speed of AccountRight 201x. I would recommend taking a look at Help Article: Speed and performance tips which contains some tips for improving the speed that has worked for some clients. Please note that it doesn't work for all users and all systems.
AccountRight 2017 will pull information from when you first open that window. If changes are made then the window does need to be refresh so that the system will relook at the database to gather information. This can be done using the (green) refresh arrow on screen or via the Update button. In the case of windows that have an account balance listed in the top right such as the Bank Register, the full window would need to be closed for changes to be reflective.
While we do indicate that you can bring across your customise forms from AccountRight Classic it is always a good idea to make sure they do migrate across correctly as further customisation in AccountRight 201x may be required.