I have the same problem using 9.0.5.1648. For me, it is triggered mostly by the "view table" action. I don't use Remote Desktop.
The view table action takes about 4 seconds of flickering, then the UI stabilizes.
The worst part is that this 4 seconds delay increases exponentially if I try to view multiple tables by selecting them first, then using "view table" on the selection.
For example if I select 12 tables the rendering doesn't finish for at least 24 minutes (twenty four minutes). It seems opening multiple "view table" windows simultaneously triggers a huge redraw storm, each window generating redraw events for the other windows, that in response generate other redraw events, and so on.
While this happens, it completely saturates one CPU core.
Closing a "view table" window is also slow, about two seconds, for similar reasons.
To understand the exponential nature of the problem, see the following table:
[Number of selected tables] -> [View table rendering delay]
1 table -> 4 seconds
2 tables -> 6 seconds
3 tables -> 9 seconds
4 tables -> 66 seconds
5 tables -> 190 seconds
6 tables -> 270 seconds
12 tables -> 1440 seconds (actually more then that, but I killed it after 24 minutes)
This is not something new. I've been using PL/SQL Developer for 10 years, and I've always had similar problems when using many windows.
But I find it unacceptable that in 2012, on system with a Core i7 quad core CPU, 8 GB of RAM, SSD, and 1024 MB video card I have to wait minutes to open a few tables.
I think it may be a good time for a full rewrite of the application using a modern framework, like .NET or, even better, Java. Especially when many people that need this application cannot use it because they use Mac OS or Linux.
I uploaded a video recording to document the issue.
http://www.mediafire.com/file/tpx5mfoj4oo14gc/WP_20120201_171033Z.mp4