I really like the look and feel of Roundcube, but one thing bugs me a lot. Every time you do anything (open a message, open a folder, etc.), Roundcube opens *every* folder and checks for unread mail. I have 25 folders, some with over 5000 messages. It takes entirely too long to do this every time I want to read one message or check one folder.
Just for comparison, when I use IMP, it only checks a list of folders I tell it to for new mail. And it only does it when I log in and at a certain time interval set by me.
David