I test sometimes with a 1Ghz machine with onboard graphics - it is sluggish but usable.
but I develop on a 2.27 Ghz laptop with I5 Quad core and 2.5 Gigs on memory (not controlling a machine)
Gscreen will always be a bit of a resource hog. price we pay for flexibility and ease of development.
There are a few things to try:
Your base thread or servo thread can be adjusted to give linux more time to update graphics.
Not sure what kind of machine you are running or whether your using hardware cards to step/servo with.
I have the update rate set a 50 milli seconds I could change it to 100 I think this is what AXIS uses.
A add on graphics card could help if using onboard graphics
The jump to the right is noticeable on my slow machine and not on the fast machine.
I assume your trying the default screen:
switching back to the main screen can be done by the bottom right button ( it toggles between manual, MDI and Auto) or touch the 'main level' tab.
You must be out of Estop and machine on for the bottom right button to be available.
The custom screen options are really very new so are not documented that well.
Aside from the sample configs there is a wiki page:
wiki.linuxcnc.org/cgi-bin/wiki.pl?Gscreen
Of course I am still actively developing Gscreen so things can change and the wiki can get out of date.
Relatively easy custom screen development is one of the goals of Gscreen so yes please feel free to use it to build your screen.
If you need some changes to Gscreen to help let me know and we can talk about it though my primary goal is to get Gscreen finished.
The first goal for you is to build the basic screen in GLADE and have Gscreen display it without any of the controls working.
feel free to post your glade file or message me privately.
Chris M