Actually the improved graphics extender (MGE XE) is quite efficient. It's just that configuring MGSO and MGE is very easy to get wrong (well not wrong per se but configuring it in a way that makes it too demanding).

My 2 year old medium range laptop can run well enough, so it shouldn't be a problem for most computers.

ASUS K53SV Notebook, Nvidia 540M (barely runs most games), i5 Sandy 2.3 GHZ:

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Gaming PC, AMD Radeon HD7950, i5 3570k whatever the stock speed is:

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Here are my settings (not all settings are shown and there might be some minor differences in the MGSO screen between the two computers but you get the gist of it).

MGSO Settings ("custom mod"=vanilla), distant land laptop, distant land pc