mate-panel continuously increasing memory consumption goes from 40 MB to way beyond 400MB. Using the out of box configuration with only 2 applets netspeed and workspace switcher added. Please refer to the screenshot.
Logout and login restores lower consumption which again goes up to the same level in a few hours.
Note: wnck-applet also has a similar problem and it crashes over 100 MB asking to reload the windows switcher, workspace switcher & show desktop.