For months now I've been using RDM for but something is changed.
The program and the Mac OS starts to lag.
When I am connecting to anything (windows) it's impossible to use because is working very slow.
I'm running MAC PRO El Capitan, 12GB RAM, 2 x 2,66 GHz 6-Core Intel Xeon
Any thoughts on this before?
I'm sorry that you're experiencing performance issues.
Can you give me a better time frame of when it started to lag? One month ago? Two weeks ago?
Was it right after an update?
What version of RDM are you currently using?
It's just a guess, but could you try switching off the Supports Automatic Graphic Switching in the Remote Desktop Manager.app Info.plist? To do so, just follow these steps:
In the folder where the Remote Desktop Manager.app is located, right click on Remote Desktop Manager.app and click Show Package Contents:
Go into the Contents folder. In it you will find a file called Info.plist double click it, it should open an Xcode window. Change the Supports Automatic Graphics Switching from YES to NO:
Start the application again and tell me if it seems better.
Much better now.
I'm glad it helped you, we're going to add an option to change it in the preferences window in upcoming release.